New System...RAID Question

Building a new system, parts are getting in today. The only thing I will be keeping from my old system is my 74GB WD Raptor which just has WinXP Pro on it. But I will be reformating it because I got Vista Prem. x64. Im getting a new SATA hard drive to replace my IDE hard drive (640GB). I wanted to installed it on a RAID0 since I read it does boost your performance a bit. But I had some questions in mind since I have never set up a RAID before.

1 - Do the hard drive need to be the same? (Size/Speed/Brand?) They are both WD drives, but one is 74GB @10k RPM and they other is a 640GB @7200 RPM, the they are both SATA drives though.

2 - Would I be better off as I was on my old system where I just had Windows only on my Raptor and keep data/programs on the salve drive?

3 - If I can set up a RAID with the hard drives I read you need to install drivers for the RAID pre-windows install with a floppy and I dont have one, Is there an other way? I also read that Vista has most RAID drivers on the disk so you dont need to install from a floppy.

Thanks for any help/tips..!