i was looking some os's for my PC its a p|| 266 mhz with 32mb ram
That's pretty old by PC standards... what you want is either Linux, or an old copy of MS-DOS. Don't let anyone talk you into buying Windows NT, 2000 or XP - those are very nice OSs, but your computer will crawl with them installed. I suggest looking at 2nd hand shops, you should be able to get something there (Linux you can just download if you have the bandwidth). The OS you buy will be determined by what you want to do with it - if you want to run old games, go with MS-DOS 6.x. To run a firewall or a fileserver, Linux is pretty good. To run other stuff, either Linux or DOS, depending on exactly what you want to do.
There are other OSs, but the amount of software available for them is pretty small.
I just remembered, there's something called Open-DOS, which is supposed to be 100% compatible with MS-DOS. It's not Microsoft, but it is SCO...
