os Broken?

I recently updated my desktop computer with a Nvidia GeForce 7600 GS (agp slot) and well we went to bestbuy (well geek squad) to upgrade it, they put a disk in and told us that one, we had a winlogonhook trojan and 2, our OS (windows XP) was "broken" but we've never ad ANY sort of problem with the OS, Now all of a sudden this trojan is acting up, and it screws up my computer enough to well, it froze up everytime i restarted it (i was in the process of removing it, and my internet kept giving out, and dls froze and stuff) so since it froze everytime on startup, i did a system recovery. Once it finished it would restart....and restart....and restart....and restart...and...and well i think you get the point... It goes to a black screen saying my video card and ram and stuff, to the HP Logo then it goes to a black screen, couple sec later it goes to the Microsoft load up screen, sits there about 20 sec, and then it goes to a black screen...my monitor turns like a brownish color(from green) and it like restarts it keeps doing this over and over and over..and i have NO clue why...Now i dont no if its my OS or if its something i did while i was trying to install my new video card, but this is just getting old...and ive tried removing the graphic card and doing a recovery, still no effect what so ever...So can anyone help me? and im dead serious when i say id love u...forever...=)
thanks all at Major geeks, ur all a big help =D

Specs:
512 gb ram
2.2 ghz
Amd anthlon xp 3200
default vid card is Nvidia GeForce MX 4
120 gb hard drive
OS=Window XP
and thats about it, thanks guys!

 

Can you go to safe mode?If you can,then log as admin,and right click my computer>properties?advanced>startup and recovery,and uncheck automaticaly restart.You do this cos you want to see a BSOD(blue screen of death),and you can see there what is wrong with your comp.If it's allright what TimW said,and you can boot to OSI recommend Avast,cos you can set boot scan when you install avast.

BTW:WELCOME TO MAJOR GEEKS!!!!!

 

No i cant go into safe mode, ive tried f8 at the begin if bootup, but the screen needed does not pop up so i cant go into safe mode, and im not really sure what vga mode is, but the rs is in an infinite loop, so im not really sure what to do...

 

If you have your Windows CD, you can try a safe reload of the OS, or if you don't need to save any data, just format and reload. But, you say that the F8 Windows Boot Options screen doesn't come up. What happens when you press F8? Are you sure that you're pressing it right when the first POST screen comes up? This is the screen where the PC or motherboard logo comes up. Just start pressing F8 repeatedly until the Windows menu comes up.

 

Ye i try that, doesnt work, the screen just wont come up, usually theres a black screen on boot up that says press f8 for safe mode and something else, but it doesnt show up

 

Again,did you set the first boot option in BIOS?
Try to press F8 repeatedly while the first screen come up(when the comp check the hard drive).

 

Ye but i dont no where the cd is, or if i we even received one when we bought the computer, which i believe we did receive one. but if i cant find it, is there any other option i can do? i mean i can go to the f8 screen and ive tried the options that i no of, like safe mode and vga, and i tried going back to last good configuration but it says windows could not sart because the following file is missing or corrupt:
/WINDOWS/system32/config/system

so obviously it needs a repair, but i was wondering if i would be able maybe to like copy the file from another windows xp OS or something, not exactly sure heh...lol thanks guys =)

 

wait, guys, how can i make a backup of my system files and all that on my laptop so i can use it to fix my desktop? says in the manual u need to make the disks manually because they dont come with the computer

 

Are you sure your monitor is ok fine? Also on the back of your tower is the monitor pluged into it correctly? If your sure its going to the new card maybe try to move it to the default slot.