FWIW, since you have some time, give it a couple of weeks. If there isn't an update, go for it. Unless you're an extreme power user, you most likely won't notice any difference between a Core Duo, and Core 2 Duo. The current machines are quite capable, and listening to someone yack on and whine about it not having C2D yet isn't really helping the average user.
You could also get one of the "refurbished" units and save a little bit too. The only essential difference is the refurbb come in a brown box instead of a white one. However, with a student discount the difference in price might not be a consideration, as I don't think that the refurbs apply, but you can always check.
I perosnally don't see Apple adopting the entire Santa Rosa platform, and it's the chipset that will make the biggest difference with the C2D processor. This chipset is, or all but is, ready from what I've read around the net. With this in mind, it wouldn't surprise me to see the new chipset in the upcoming updates. My best "guess" right now from all the information available is that the C2D processor simply isn't much to talk about until it has the tools it needs. An average 5% bump isn't much if it can't fully support 64-bit operations. Hence the possible wait being in part to the new chipset, which is ready or all but ready. While this chipset will be part of the SR platform, there's more to it than that.
As already mentioned, if you're seriously considering a Mac, there's more to it than just a little "2" in the name of the processor. From this side of the fence, the pro's outweigh the con's in the little number. You either want a Mac, or you don't. If they had PIII's in them, then it would be a consideration. However as it is now, CD/C2D isn't much of a sticking point yet.