Am I clean of nasties? Computer still not going as fast as when i got it.

Ok, I have tryed many antispyware, antivirus things and such, but my computer still likes to randomly crash, and go very slow at random times. I've gone through all the manual HJT deletions, and downloaded almost all of the programs. Somehow its still going slowly. I have Windows Xp, pentium 4 (2.4Ghz), 512 ram which seems sufficent enough.

My computer didn't come with the installation CDs and i definatly dont have enough money to buy windows xp. Defrag is a good idea thankyou.

Edit:

I did the defrag, it told me i didn't need to, but i did it anyways, it did NOTHING.

post some config info:
from the CP->System->General

installed ram

from the CP->System->adv->Performance->Setting

virtual memory size

hd capacity and free space

504Mb Ram

754 Virt Mem

Used Space around 67 gigs
Free Space about 38

First Read: Only use these HJT-instructions when asked!
/P/ Process needs to be stopped
/U/ UNinstall anything to do with this
/R/ unRegister the xxx.DLL in that line
Transfer the text from between these dotted lines underneath to between the dotted lines of that post.
Make sure to follow ALL instructions in SEQUENCE, and in HiJackThis tick/fix ALL lines indicated here!
...................................................................................................
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyOverride = localhost
/R/U/ O2 - BHO: XBTP07618 - {2296428D-C133-4928-B76A-A200FF409572} - C:\PROGRA~1\FREEPR~1\freeprod.dll
O2 - BHO: (no name) - {FDD3B846-8D59-4ffb-8758-209B6AD74ACC} - (no file)
/P/U/ O4 - HKLM\..\Run: [MsUpdate] C:\Program Files\MsUpdate\MsUpdate.exe /auto
/P/ O4 - Startup: PowerReg Scheduler.exe
O8 - Extra context menu item: CR: &Import Data - C:\WINDOWS\web\CR-ImportData.html
/U/ O8 - Extra context menu item: Download all by Net Transport - C:\Program Files\Xi\NetTransport 2\NTAddList.html
O8 - Extra context menu item: Download by Net Transport - C:\Program Files\Xi\NetTransport 2\NTAddLink.html
Unless these IP-numbers are from your ISP, fix this O17
O17 - HKLM\System\CCS\Services\Tcpip\..\{C74F3DF8-5193-40EB-AFBE-670DB08CC0EF}: NameServer = 67.18.100.114,198.41.0.4
O18 - Protocol: msnim - {828030A1-22C1-4009-854F-8E305202313F} - "C:\PROGRA~1\MSNMES~1\msgrapp.dll" (file missing)
O20 - Winlogon Notify: rndunkwn - rndunkwn.dll (file missing)
O23 - Service: Remote Packet Capture Protocol v.0 (experimental) (rpcapd) - Unknown owner - %ProgramFiles%\WinPcap\rpcapd.exe" -d -f "%ProgramFiles%\WinPcap\rpcapd.ini (file missing)
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And just in case, do not (re)install Limewire or any similar P2P crap!
Next time you're on your own!