I disagree that this is in any way a rip-off.
If I bought a car last year and a newer model came out this year, I certainly wouldn't expect the manufacturer or dealer to be obliged to supply me with the latest model, just because one is available.
You can download SP 2 and slipstream it into your XP Pro disk and burn a new CD, then use it to install over XP Home if you want to.
Microsoft offered SP2 as a CD for nominal delivery costs and anyone you know with broadband could easily download it for you if you cannot do it yourself. I supply many friends and colleagues who only have narrowband Internet access with large Windows updates on CD this way.
If you want some links on how to create your own slipstreamed Windows CD (it is quite legal to do so) feel free to ask. Running a few Google searches on slipstreaming XP SP2 will give you the full lowdown on the subject. It isn't very hard to do.
Microsoft offer their updates online to anyone who wants them.
Incidentally, if you choose the clean install option rather than the Upgrade (recommended) option when trying to install your XP Pro disk, it should work just fine. You will lose any ability to roll back if things go awry, but you should be able to install and then update XP Pro, but you need to make certain you have all the necssary device drivers for your system, as well as any application software you want.