What OS should i put on my old IBM ThinkPad 600?

It is loaded with trojans and viruses spyware and everything else( more than 200) . Im hoping for a free OS. I plan on spending no money.It has a Pentium II and currently runs Windows 2000 Professional. It has

159.36328 MB RAM ,

233 or 266 MHz ,

4.01 GB hard drive

-Greatly appreciative,

Sean

What OS should i put on my old IBM ThinkPad 600?virus removal

if it runs 2000 ok stay with it ..

What OS should i put on my old IBM ThinkPad 600?anti virus protection

Maybe the best is Windows 98. If you put Windows XP, maybe tour computer gets slow.
Wow - a four gig hard drive - hardly enough to run Ubuntu although it meets the minimum requirements. If you are just messing around - give Ubuntu a try or maybe XUbuntu (lighter weight) - it is free - at least you will not get reloaded with spyware and junk. :)

Download Ubuntu here:

http://www.ubuntu.com/getubuntu/download