Know the feeling mate, I assume you can still access the web from your PC.
Try this site, I've found it to be spot on in the past (all their advice is pukka)
http://www.bleepingcomputer.com
It helps if you know what trojan, virus etc you have so try downloading "spybot search & destroy". It will probably identify the problem, even if it cant fix it, then search bleepingcomputer for the removal tool.
Good luck