I am currently looking for an external hardrive, at least 200gb, to use for data storage, but mainly to partition for different os's. i want to put on mac osx, xp, vista, and linux. im not sure how i will get osx on there, but i will find a way. however, does anyone know if have an external for this partitioning will sacrafice speed (because of connection type) and if so, should i use firewire/eSATA. and will it also make the os's portable? if i could do this it would be sweet...

You being able to boot from your external hard drive depends if your computer will recognize it as a drive. I have a dell and it recognizes my internal cd-rom drive, hard drive, floppy drive, and usb disk drives, but it does not recognize my external dvd-rw drive. I doubt that you will notice a difference in speed with all the fast connections like USB 2.0, and firewire and eSATA. The hard drive itself probably won't even be able to come close to the maximum speeds that those ports have.

Alright, but will the brand matter, i mean, higher quality ones might go faster, or w/e. because u can get hard drives that go up to like 15k rpms, which is insanely fast.

So far its impossible to run OSX on a PC. And I think its better to simply install one main OS, The one you're gonna be using the most often and then install each OS on top of that virtually, using something like Virtual PC 2007. If you have a decent PC, it'll run smoothly. However if you plan on running games on both Vista and XP, I'd suggest installing them separate on different partitions.