I don't live in the US so I'm not too sure about shopping there, but here in Oz it's often cheaper to have a PC built by one of the smaller stores, rather than go with a propriety brand with features you neither want or need. Not only that, besides getting exactly what you want in your PC, it's better in that you also avoid the bloatware big manufacturers all too often load on their systems.
Also, Shaunna (mrs starkers) uses a few of those programs (Apophysis, PSP8, Artrage2, CorelDraw and others) on Vista without issues. Your printer will most likely have driver support for Vista also. I can not say for sure if your Maxtor OneTouch would be compatible, but I imaging that it would be if it's a 'plug and play'. However, if you'd feel more comfortable with XP, then the smaller stores would install that for you, I'm sure.
As for the LCD flat screen monitors, while they take up less desktop space, it's a matter of personal preference. Some people swear by the old CRT monitors, especially for graphics work, while others prefer an flat screen for sharpness & clarity. If you are not too sure, I would suggest that you shop around where you can actually see the monitors in action, and can compare/even trial them in-store, and go with one which most suits your needs, rather than have to buy 'blind'.
I have no experience with laptops whatsoever, and it's just my opinion for the desktop, but I'd be inclined to go for a non-branded PC, if it were me... if that helps at all.
Oh, and beware of technically inexperienced sales-persons with the gift of the gab, who may try to palm you off with something you might/could regret later... also, be certain you're happy with your purchase before leaving the store, etc, etc.
All the best with it, then, and happy shopping.... starkers.