You've got it backwards (many people seem confused on this today 😛).
Patch cables (as you would buy at CompUSA) are, indeed, just short ethernet cables, generally used for running between patch panels or for going from, say, a cable modem to a router or NIC. The only times they're really useful are if you're trying to make a very short run and you want to keep the cables neat, or if you need *one* short gigabit connection between two switches or something like that. Otherwise, standard cables work fine -- cat5 10/100 ethernet goes up to about 100ft with very few noise problems.
Crossover cables (or, technically, "Crossover patch cables") are used for direct PC/PC connections. They're also used to daisy-chain hubs and switches, but almost every switch and hub I've seen in the last few years has an "uplink" port that does the same thing internally, so you almost never need crossover cables nowadays.