start->run->msconfig

In the services and startup tabs find anything suspicious and record the names.
Type the names into google to see if their viruses. If they are:

start->run->regedit

In the 'find' dialog, type the names that registered as viruses on google (Do NOT type the virus' name, you must type what it was called in msconfig)

Keep pressing F3 until you find entries like 'run"xxxxxx.exe"', and delete them.
This works for almost all viruses. Very hard to escape the registry.