Guys (and gals of course), post up what you think is good for your PC as in system utilities for cleaning/tweaking your PC and such.

For me, my prefered stuff would be:
Kaspersky Internet Security
Spybot Search and Destroy (well, barely run it anymore since KIS as everytime I run it, nothing comes out, even after updates, but my KIS is picky) And don't forget Teatimer also.
CClearner - Cleans up temp folder and redundent stuff off the HDD without leaving damages, aside from more space, HDD wise.

Well, thats what I have on my PC. CCleaner and Spybot are freewares, so kudos to the makers for making it free and powerful at the same time.

Older times, I used to use:
HijackThis

and a few more which I cannot recall.

well, i now had Avira AV, spy bot S&D, CCleaner and hijackthis in my computer..
found those softwares quite useful tho..

for entertainment, i have real player, media player classic, winap 5.51, windows media player 11, jetaudio 6, and TTpayer.

download managers i'm using bitcomet and Ares..

thats wat i have in my laptop

Addition from me:

Recuva - From the same developer as ccleaner, helped me recovered lots of accidentally deleted files from flash media before. Just don't expect it to be something to start your own data recovery business.

Axon Data's AxCrypt - Encrypt a single file in 128bit AES. Receiving end gets a self decrypting .exe file.

Truecrypt - Encrypted virtual drive. 256bit AES. I use this to replace the write-lock function on USB flash drive.

TreeSize Profesional - See your HDD's space allocation, know which item takes up most space, helps when I want to clean out my HDD.

Swissknife - cuts your partition up. rarely use it, but when I need it, it's the best (for me).

MS Applocale - No need restarting to run program that is not supported under english windows... kinda...

Diskeeper - skip the baby diskeeper that comes with windows and go for the big brother.

mine
Antivirus and spyware:
1.KIS (kaspersky internet security)
2.Spyware Doctor
3.Winpatrol

Utilities
1.System Mechanic 8 - anything for your pc from cleanup, antivirus, firewall, recover, freeing ram,etc
2.Tune up utilities 2008
3.Diskeeper 2008
4.ACD See (edit picture)
5.VMWare (virtualization)
6.Roboform (save your password)
7.Paragon partition manager (manage partition)
8.riva tuner + amd graphic tools (graphic management)
9.speedfan (fan management)
10.sisoftware sandra + lavalyst everest (benchmarking)
11.Daemon Tools lite (virtual disk)
12.flashget

Work
1.Adobe Master collection cs3/cs4
2.Visual studio 2008

Visual
1.Object dock and icon packager from stardock

Aside from Recuva, you can use PC Inspector File Recovery. Its a freeware also. Good for recovery in case accidental deletes but remember not to do anything on that drive if you accidently deleted stuff as new files will be overwritten.

Firewalls recommended:
Zone Alarm (picky)
Comodo Internet Security (never tried but I heard its good)

Do check this link out for nice freewares.

I love freewares and freebies, rather than pesky paid for stuff which never really works well.

Stuff I use:
Winamp (hey, its free)
foobar 2000 (free again)
K-lite (free )
7-Zip (free~)
uTorrent (still free)
BitComet (also free)
Filezilla - For ftp usage (free too!)
Audacity - audio editing (free also)
Adobe Acrobat Reader (what do you think?)

I just have too many freebies on my PC, and best of all, quite a few of them are open source. Linux user should know how we work.

For benchmarking:
OCCT - processor and ram benchmark (free)
CPU-Z (free)
GPU-Z (free)
Everest Home Edition (used to be free, but no more now)
Aida 32 (used to be free also, but old stuff)
3Dmark (free demo and preset tests, also free)

I'll add on what I do come by, and also what others mention.

Addons:
Open Office - Like MS Office, but its free.
Foxit - PDF reader and much more
Microsoft Reader
CDisplay - for manga/comic readers
yBook - Downloads directly from Gutenburg (totally forgotten bout this. Free also)

Updated 30 October 2008

i need a recovery software that is able to recover files like audio and video files.
i used a software which i don't even bother to remember the name to recover and it really pissed me off.. o hopping for a good suggestion.. thx~

@satria:

Where's Foxit and Open Office?

PC Inspector is a lot more powerful than Recuva. I use that too, only when Recuva fails. Recuva is also more user friendly.

I use foxit on my other pc and OO at work. Foxit just runs so much faster than adobe reader. Installed Adobe reader 9 the other day, I think I have some games that install faster than it does. -__-

foxit is nice, but troublesome if you want to read e-books. no cleartype support >.>
but still...i love the adobe acrobat pro (let me create and read pdf )

foxit loads real fast. Have you tried Microsoft Reader? Don't think I got the name wrong, but I used it to read an e-book and it was really nice to use. The loading time was quite good as well. I still find Adobe Acrobat as too time consuming. I suspect I may be one of those people who would be huge fans of e-paper technologies and would buy them.

yep that microsoft reader. i use it sometimes to read ebook (.lit) if i dont have the pdf version. somehow..its nicer to read in pdf (especially those black background screen when the paper is a4 so cant be full screen read )

adobe also have antialias support for font..dang its really nice (as long as your graphic card can handle it)

or sometimes...i use microsoft word to read..(sometimes my ebook collection only have .txt ...reading in notepad is just...plain hurt )

truly foxit is nice for those who have light computer, or notebook

Well, since we're talking about ebooks, I use ybook to directly grab ebooks off Gutenburg. Free too.

Anyway, I'll update my 2nd post with new stuff as I see it or you all mention it.

Gutenburg is free in the first place.

I was noting both ybook and Gutenburg.