It's not that bad..
If you suspect you have a virus (or any other malware), you should take steps immediately. The following procedures work for most viruses or malware (except perhaps for completely new, unknown or unusually malignant strains). It is better to complete all steps, so you can be (reasonably) sure that all traces have been removed.
Signs to look out for (infections may cause one or several of the following):
- Slow computer, and/or slow internet connection.
- Strange pop-ups or web browser redirections (beyond those expected from dodgy websites).
- Program failure, or inexplicable errors (even after a fresh install).
- System functions unavailable (eg: Control Panel, Task Manager, Internet Explorer).
- System giving a "RPC error", giving a window with a 30 second countdown to a restart.
- Excessive internet cap usage, i.e high internet traffic on your computer.