|You can NOT install Vista on the C: partition, it MUST go on the D: partition. What you're going to have to do is repartition the drive so that you have 3 partitions...C for XP, D for Vista, E for storage.|
That can be easily done using EASEUS Partition Master which is available for free:
Here's some screenshots to give you an idea of what you'd be working with:
All you have to do is split the C: partition into 2 parts...you'll have to decide on the size of each. Once they're created, here's the easiest way to setup the dual boot:
- boot into XP as usual
- pop the Vista disc in the drive & wait for it to spin up
- when a screen pops up asking if you want to upgrade (recommended), click 'Advanced' instead, then direct Vista to install onto the new partition that you just created. From there, just continue on as a normal installation...the boot menu will be setup automatically.