IMHO, don't use linux on top of windows. It'll give you false idea on linux. You're likely to crash often (which doesn't really happen with linux), be running slow cause you won't be able to use all the resources, and not have a proper environment (networking, multitasking...). If you're really small on disk space, try to get a 800 Meg partition and install RedHat 6.0. A full install takes ~550 Megs. At worse, some linux versions allow you to boot of a floppy without having to do any kind of partitioning.
For even smaller linux versions, try 'Peanut Linux'. It's linux optimized for 486 internet browsing. Pretty good.
Hope that helps...
