RMA may not be your solution, it is not hardware related and there may be a charge for software/user created issues.
You could try system restore from the command prompt, providing you know the logon details for the administrator account (wish I had a quid for every time I tell someone to create a password to log on with):
1. Hold F8 to get start up options.
2. Select Safe Mode With A Command Prompt
3. Logon using Administrator and password (if you have a password for your account and it was auto-logging on use the password for that account).
4. Run this command at the command shell (DOS Box): %systemroot%\system32\restore\rstrui.exe then press enter.
5. Follow on screen prompts.
This will only work if you have the password (if it is blank then try just hitting return) AND you have not disabled system restore.
Again, for others to bear in mind, You MUst Always Log ON to Your System With A Password, it is your first line of defence against malware/trojans/hackers and is your last resort if your driver install goes tits up, because until you logon XP keeps a copy of the old configuration, once you logon it is destroyed and you cannot easily roll-back with Last Known Good.