My experience with the JB drives is that overtime they get very very loud, to the point where it's impossible to be able to stand it (yes I RMA'ed it and got other ones sent to me, same problem), i ebayed it, and got myself a silent seagate, as for the 8mb cache, it should not make any difference in loading times like someone said, the only notable performance difference is in pcmark tests which heavily involve the cache, however those are not real world.
About the noise, it bothered me, it doesnt bother some of my friends though, but i prefer quiet. 🙂
A bit of advice to you would be to get a Seagate Barracuda V, bout the same performance, plus u can get a SATA 8mb cache version if u want. Maxtors are also supposed to be quiet now, but I havn't tried a new one yet.
-Mark