BSODS NEED HELP!!

Hi ALL, lately my com had lot of BSOD
i just cleaned my com fans and heatsink etc.
it seemed to help a little but i still get bsod after 1 hr of low grahpics gaming on maplestory.
I used to be able play higher grahpic games at med settings but i dunno what casuing the bsod.

Computer Specs:
Intel P4 2.4Ghz
Compaq Presario
MSI-MS-6575 Motherboard
1GB Kingston DDR ram
( i had 1gb+ my old 256mb ram it was 512mb ram one of the 256 burned , used to use 1.256GB)
and PSU i tihnk about 240W
Geforce 7300GT 512mb VGA
and Realtek AC,97

Problem is i added 1gb ram +my 256mb when one burned like only last year so only about 1 and half yrs and the VGA changed only this year about 6 months, about 1 month ago the computer was fine i can play most games at med grahpics
now not more then 1hr it start getting bsods.
what is casuing it i dunno
i run metest86 etc i dont see any problem be caused by overheating when playing games it goes to 58oC if not is 45-48oC but if it lacked Power why i can play fine for 6 months.
BTW if u think is ram etc this are stuff i run and checked b4:
metest86 RAM OK
ComboFix fix all errors
Hijacked This fix all bugs
i have had some spyware malwares
not long ago since my bsod started i cleaned all i done defrgatment
clean up reformated malware and adware and kapersky website scan all everything clean. 100%!!
(what i dont understand is if it had power or stuff broken why all scans checks are fine and why my VGA worked for 6 months fine even with almost everyday running over 5-10hrs of games like COD4 L4D and
even had it on 24/7 for some days to dl animes it was all fine till now)

PLS ANYONE HELP!! I CANT LIVE WITHOUT MY COM!!