The operating system depends on the person. I grew up on Windows (First computer I had came with Windows ME, actually) and I have used every version since, so I know quite a bit. Mac is one of those operating systems some consider to be user friendly while others say is a complete pain to use. I'm a mix of both.
Now a question about your daughter, if you don't mind me asking. This will help us here find her a good laptop. Can she see anything at all or is she completely blind? Reason I'm asking this is because of certain features that are actually built in to Windows that might help. For example, low contrast modes which makes the background black and letters white. Also a software based on-screen magnifier, and if it comes down to it, I know Windows Vista has a built-in narration program (not sure how well it works)
If Windows ME has the narration program, I'd start her out on that Compaq. If that isn't an option, I'm not sure where to look. I'm more of a desktop person. This looks nice: http://www.tigerdirect.com/applicati...198&CatId=3987
You might want to take a look at this, too: http://www.hooleon.com/miva/merchant...Store_Code=KBH
This would help her learn the keyboard faster, but I'm not sure how well it would work with that Compaq.
Hope this helps! Good luck!