Windows Vista Can I Use Vista and XP Machines Together?

I use a Dell XP home machine at work which is fine for my needs.

I've got an old XP home laptop (Celeron) at home that's old and crippled, and I'd like to replace it. But I'm not sure I can find a new laptop with XP, and even if I could, I don't know if it's necessary.

I mean, is there any reason why I couldn't run Office Outlook and Word 2003 on both machines, and swap files and check email on both?

Are there any compatibility or other issues that require me to have both machines running the same OS?

Thanks for any thoughts on this.