so you really should ask Dell. You can't just buy any old off the shelf motherboard. Also bear in mind that when you replace the motherboard, you'll in all likelyhood have to replace the CPU. And then you'll still be stuck with XP or Vista. When all is said and done, you'd probably be better off just buying a new laptop. If you hurry, you can probably get one with Windows 7.
Hoarding photos on your phone?
Those picture are hogging memory and could be slowing down your phone.