Win 7 RC - expires soon, but best OS ever.
Win Vista - You can buy this + upgrade to 7 (needs lots of memory, takes up good amt. of HDD space)
Wind XP - Dirt cheap, fast, not too pretty
OSX - Not for everybody, pretty, only get if you've researched.
How does this help the poster? I am not trying to be a jerk here at all, but lets look at what you are saying.
A release candidate is the best OS ever? Yeah because I want to run my comic and writing business off a beta OS....
Vista, you are saying it needs lots of memory? Lots of memory to run a comic and writing busienss?
XP - you say it is cheaper but not as pretty? Does that affect the posters position, wants, needs, or requirements?
OS X - only get OS X if you have researched it? WTF does this even mean?
None of this is relevant advice to what the main poster is offering. All of this does is going to confuse the heck out of them. Most people make assumptions or like to give out misinformation when it comes to qualifying someone for what they need, versus your opinion.
Let me start over since I kind of did the same thing, but I did recommend they get the Mac and for many reasons, but before I can justify it, we need to know what the OP plans on doing/using?
1) What applications will you be using?
2) What preferences do you have on an OS?
3) What needs do you have of a laptop? Portability, battery life, screen, wireless, etc?
4) what is your absolute highest budget?