Confused and need advice please

[Allnick]

Before I ask for help, I must tell you I have been lurking and reading threads for an hour or so before registering.
This looks to be a helpful forum. Well done to all concerned.
I hope this in the correct forum, Please move if not.

I need some advice please.........

I intend to buy a laptop.
I need complete mobile access to the internet and have researched the connectivity side of things.

My problem (if there is one) is that I have read on various websites that "Windows Vista" isn't compatible with some software.
I use Windows XP Home on my desktop computer, and need to be sure that I can install the same software to a laptop.

Therefore I would ideally like to buy a laptop with a reasonable spec, and Windows XP Home.
It's proving difficult. All the high street shops sell laptops with "Vista" installed.

I really need XP Home to be certain of no problems instaling stuff I already have paid for.

Sorry for the long introduction.....the question I have is....

What is the difference between Windows XP Home and Windows XP Professional.(widely available on the net)
Will software that loads and runs on "home edition" load and run on "Pro".

Many thanks for any advice/comments.