Well, I'm pretty sure that those recovery discs are only partial to you're motherboard/component setup. I highly doubt that if you change the HD that it wouldn't let you install. I would definitely get the same brand though.
This is my theory:
Say you buy a dell (I chose dell only because I know they give you a recovery disc rather than an OEM windows xp), they hand out the same disc for just about every model. So what would be the difference between using it on a 60gb comp or an 80gb comp.
Anyway, I bought a non-computer-specific dell recovery disc online for my parents dell since they lost their disc. It worked like a charm, so I doubt that those discs are HD Specific (only if you get the same brand)
Current Build (Hope to finish by late spring):
Intel Q6600 g0
Asus Maximus Formula
geIL Evo 2GB (2x1gb) DDR2
ATI HD3870 X2 or Nvidia 9800 X2?
2x 150gb RaptorX (Have it)
Thermaltake Toughpower 750w PSU (Have it)
Antec P182 Case
HP w2207 22" Monitor (Have it)