MyPassport Essential - Win XP Pro & Vista home Pro interchangability

I just bought the drive and want to know if I can use it with my two PCs.

Desktop runs XP Pro and Laptop Vista Home Pro.

I bought it to back up photos, and media, as well as Documents.

Before I try it I wanted to know:

1- will it work with both operating systems?

2- If so, Should I use it first with the Vista laptop?

3- Any suggestions?