If you're a home user and are going to have your PC hooked up to a cable/dsl modem and nothing else.
Use Home.
If you're going to want to run a domain, or do more extensive things than basic apps, games, internet browsing, you'll want to look at Pro.
Home has simplified security. Meaning eveyrone who uses the computer is assumed a trusted source, like your family.
PRO has security that you can say some people might not be so trusted so let's restrict what they can do..
Most people who aren't heavy into doing company level networking, a domain, won't need PRO.
If you plan on running a Domain, use PRO.
If you don't know what a domain is and you don't have an extra computer for a server and you trust everyone in your house.. trust they won't intentionally ruin your computer, use Home.
Home is for home users, Pro is for people who are heavy in the networking side.. it's geared toward Companies that most likely have a full time IT department.
Regardless of what people say.. most will say Pro is better even when they don't use a single feature with the Pro version. They just want more.
If you're going to buy a version.. chances are Home will do what you want.
But! If you want to go 64bit someday, you'll need the Pro version (at this time) to upgrade to 64bit. Home version doesn't get a free upgrade.
Why?
Because 6 bit is going to be geared more towards companies that need heavier processing of their computer for work. Home PCs rarely need that power under almost any condition except gaming - and even in gaming, it probably won't be needed for a while as most higher end PCs will run.