Problem Upgrading Windows XP?

Just to see if anyone knows about this. I recently got a really good deal on an SSD (Solid State Disk). Patrick Norton said you shouldn't just 'clone' your hard drive to an SSD, you should re-install Windows from scratch, because it will install differently.

So I re-installed Win XD (4 year old Dell, Pentium IV). It worked fine, and the computer does seem a lot faster. But when I went to the Microsoft website to download upgrades, I find Service Pack 2 won't install. It downloads, then says there's not enough space on the disk. But the disk is freshly partitioned and formatted, a 60 gb disk with >55 gb left on it.

Anyone have any idea what the problem could be? Microsoft, of course, no longer supports XP (but I like it!)

Extra credit question: Think my old computer would work any better with Win 7?