I've never really liked laptops. I don't like the constriction, relative lack of power, difficulty of upgrading, or the cost. I've been programming and gaming for 20+ years. I prefer a natural keyboard, wireless optical mouse, and huge 22" CRT. The tiny keyboards with whacked layouts, mouse substitutes, and tiny displays of laptops make me cringe. Granted, you can plug in other devices or dock your laptop - but IMO, if you're going to go thru all that hassle then why have the laptop in the first place!?
Next - I think anyone who's serious about gaming should have a decent computer running Windows XP. XP is exceptionally stable and works great for gaming (with 1g of RAM). You should also have a decent graphics card. Anything less, and sorry, you're not very serious about gaming. Get a job, get a 2nd job, get a credit card - sell your soul in some way and get a decent computer!
So, IMO, games should be developed for XP and desktop PCs and if they happen to work on lesser machines (or other OSes) used by the minority then that's a bonus.