Windows would do what you want but a Mac does it better whilst looking better too
The same specs are irrelevant as the hardware in Macs on average are faster, the Macbook's screen for one is a lot better. Plus, the programs that run on OS X are much more efficient and improve your workflow a tonne. Macs don't get as many viruses and don't need you to install loads of anti-virus programs that do more harm than good.
For video editing, I'd go with the 15" MacBook Pro and try and get the i7 processor for the best performance
You've got to realise that with the OS, Windows XP is 10 years old. Mac OS X is bringing out better and better and each time it only costs $35, as opposed to $100 everytime Windows bring out a crappier version of XP. Snow Leopard OSX 10.6.5 is a 64 Bit Processor and gets updates all the time
Also, if you really want to run Windows XP, you can get a program called Parallels and run any Windows program through your Mac. You can't do it the other way around.