ASM gives you several other benefits.
It improves the filesystem overhead over ext3, and deals with having to concern yourself about file paths. Most Oracle documents will assume you have ASM - I think it's worth it.
I'll be using Solaris 10 (UFS) for the OS. Still worth it? And what about the one disk question? If I'm only using one disk is it still worth it? I thought ASM was a way to separate disk IO which doesn't make much sense if there is only one underlying physical disk. I could be way off not being an oracle expert. It isn't a gigantic DB by any means (less than 100mb) either so are there still benefits when using in a VM?
You have only one disk and a 100Mb database? In this case, ASM is probably an extra layer of complexity that you do not need.
ASM is best suited for spreading data across many, many spindles and in cases where database space management is a consideration.