Try Spybot or NOD32 trial version to see if that removes it and run the AV in safe mode like Sek3o1 mentioned, you might need to turn off your system restore as well till you have removed the virus then turn it back on.
As you don't have the OS disc's a reformat is out of the question but you should get an Image program and back up you drive so if you do run into problems you have a back up OS.(NO FORMATTING NECESSARY)
Compaq Presario CQ5305K-m Intel® Pentium® Dual Core E5300 (2.6 GHz), Windows® 7 Home Premium 64 bit, 2048 MB , Hard drive: 320 Gb, with 18.5 Widescreen
SPURS TILL I DIE (DIAMONDS ARE FOREVER SO ARE SPURS)
TO DARE IS TO DO