Not a problem.
Yeah, if you look at the specs: IDE: 2x ATA 100 up to 4 Devices. It also supports the following: Onboard SATA/RAID: 2 x Serial ATA by ICH5R, RAID 0/1.
When a spec sheet states IDE, that means EIDE on modern equipment.
ATA 100 is the speed (see Raekwon's post) of the IDE. If you wanted to go with SATA, you could. But if you are on a budget and already have the EIDE device, there shouldn't be any problems with compatibilty.
I your hdd is ATA133, it would just run at 100.
\"The surest way to corrupt a youth is to instruct him to hold in higher esteem those who think alike than those who think differently.\" Friedrich Nietzsche