Under some circumstances, you wont be able to remove the Trojan. These malware writers are pretty clever. They fix the Trojans so they will copy themselves to the System Restore folder, so even if you restore your computer to an earlier date, you'll still be infected. These Trojans may also place a root kit in the Windows folder so that it cannot be removed, and if you removed it, you'd pretty much crash your system.
There is one thing you can try...
HiJackThis: Trend Micro HijackThis - Free software downloads and reviews - CNET Download.com
This program isn't like Norton or other scanners. It inventories all your back ground objects that are running as well as some folders for malware or other nasty stuff on your computer. The scan takes all of about 5 seconds, maybe 10.
Since this program looks at all
the programs running in the back ground as well as some that might be in some of your folders, it doesn't know whats good and whats bad. So there may be 90 files that pop up on that first scan... but only two of those may be malicious.
When you install it and open the program up, it'll give you some options, one of which is "Scan and save a log file". Pick that option, then after that log file is saved, post it on this same thread so me and other members can take a look at it and tell you what you need to remove.