Good point mentioned about xorg.conf. Video will need reconfigging after the swap too; very likely.
Interestingly, @ sycamorex -- when I last did this, (it was also on a 32bit system: Slack11) and I did have the kernel configured pretty tightly for the old hardware (my mobo that died) so when I got the new mobo (which needed a new CPU, new RAM, new video cards, etc..), I put the machine back together and had fingers crossed -- and was expecting pretty much nothing at all to work.
To my pleasant surprise, the darn thing booted right up without complaint!
Of course, I DID need to do a little bit of work re: video driver, but my new video cards were of the same make as the old ones, so it wasn't bad. Plus, I soon after rebuilt my kernel, geared toward the new processor (which was of the same make too, but a much different model-- I went from an old P4, to a new Core2), but still, it booted up very nicely.
I guess with anything along these lines, mileage may vary per case, but before defaulting to "reinstall" mode, I'd go for it
, see what happens. Worst case scenario? It doesn't boot. Use the CD to boot then.
A backup is good advice always.