Can't access Windows XP

Last night McAfee popped up and notified me I had a WIN32 virus and told me it couldn't quarantine the virus. It told me to reboot my system and then run a virus scan. I rebooted the computer but on reboot a Windows Login screen came up asking for user name and password. I have never set this up so wasn't sure why I got the message. After tabbing through user name and password and hitting enter, it appeared to boot into Windows. Once the background screen came up the system automatically went into shut down mode. I've tried several time and this is what I keep getting and can't get Windows to bootup.

I tried going into safe mode as well. It starts the process of loading safe mode but before it completes the load it reboots the system.

Need help on how to clean a virus without being able to get into the Windows system. Is this possible? I have Windows Recovery Console installed but not sure what to look for so I can fix the problem and boot the system.

Running Windows XP Pro Service Pack 3

Thanks