Is Sonic Megamix worth playing btw? I might download it, but I don't want to wear out my CDX laser using a burned cd-rom.
I would say it's worth playing, yeah. It has some flaws (i.e., some bugs; also, the final boss is a pansy), but even if you only use it to switch modes and play through Sonic 1 with spindash, it's worth it.
In addition, it has Shadow (gasp! a decent game with shadow in it?) and his instant-go-fast-button, as well as the homing attack thing that can be used in either A)MegaMix mode or B)original Sonic 1 mode.
Finally, some of the level designs are really fantastic (others... meh).