Hi, I'm currently trying to convert an altered (suped up) IBM Aptiva which was originally made for windows 98 into a web server. I would like to use this to host several sites. I'm trying to choose between either windows server 2003 or linux. Anybody have any advice?

That depends a lot on your experience with or willingness to learn Linux. If you have either I would recommend it hands down. For one it is free, two you can more easily set up virtual sites (you said you wanted to run several) with just a copy paste in a config file etc.

If the sites grow more advanced you might need php or mysql integration. If you think you will need this I would set it up from the start, will be much easier.

Main advantage to a Linux box is less maintenance and will run forever barring hardware issues. Windows needs regular re-booting etc even with the server class OS.

Also if your box was originally designed for Win 98 you may have a hard time running 2003 on such old hardware where Linux will have few issues.

Ignore all this if you don't know Linux nor want to go through the learning curve on it which some don't.