Running Linux on an XP PC

I have hit a 4 Router limit when running the Dynamips Cisco IOS emulator under XP. I understand that Linux makes far better use of the hardware and would let me run a bigger test configuration.

Can anybody out there fil me in on how I could set up a specific Dynamips boot sequence into Linux whilst retaining XP for normal applications.

Also, I am a wan / router man and know next nothing about desktops!! Please assume you are talking to a cretin.

Thanks,

Colin