Formatting

Ok so I am building a new computer and am going to transfer my 2 existing hard drives into the new computer. I currently have a 250gb old/slowish hard drive and a newer 500gb WD caviar black. I am wondering how i should format the 2 to accommodate the following needs:

- I want Vista home premium 64-bit to be installed on the 500gb hard drive so that it can boot and run faster.
- I want to be able to reinstall vista on the hard drive with having all my data backed up (seperate partition for vista)
- Ideally could see using the 250gb hard drive to back up most of my data on the 500gb one.

So main question is, what size partition should i make on the 500gb HDD to put vista on. What else should go on that partition with vista? (programs?)

Thanks for any help!