Man...you can tell this kid is 14. Maybe he's even Service-14.
No capitals. Redundant punctuation. Mixing numbers and words like a AIM-bum fanatic...Gotta wonder where a 14 year old is getting money to buy SCSI drives, too.
SCSI is not for you. You're gonna spend a load of money on a drive that's only 20gigs that'll be almost gone once you load up yer mp3 archive, OS, and one (maybe 2) games. You don't really need that kind of reliability, and such reliability is growing moot anyway, as new ATA and SATA drives are near rock-solid anyway.
Go with a good Ultra ATA133 or a Serial ATA drive (if your mobo supports serial). Don't waste your time and money on SCSI. I work with a lot of heavyweight companies, and the only ones buying SCSI are the ones who already have SCSI chains from way back when they were popular.
There is a difference between EIDE and IDE, but it's pretty moot now. Few IDE drives made today are of the old strictly-IDE type. There was an Extended-chain IDE, but that's been replaced by the creation of secondary (and terciary) IDE channel ports on mobos.