Yes a SATA RAID will be faster than an IDE one, but either would be faster than a single drive. Also don't forget what I said about a controller, either your motherboard has to have the capability, or you need to buy a controller card. I don't have your motherboard, but I also have a newer Asus board, and on mine, for SATA, you can configure it for RAID in the motherboard bios (so you don't have to buy a card), for IDE, I would have to buy a card to do it.
You may want to buy two SATA drives for your RAID, and keep the IDE drive installed to keep a backup of your important stuff. Be careful to backup anything on your current drive before you start messing with partitions etc. If you have some $$ to burn, I'd suggest 2 Western Digital Raptor drives 10,000rpm. They are smaller than other drives (only come in 36GB or 74GB), but damn are they fast. With 2 74G ones you would have about a 140GB main drive, which is big enough for me, will cost you about $400 US to get 2 of these 74GB though.
Also RAID is slightly (not much) more complicated to setup than a single drive config. If you buy a card, it will come with a floppy with drivers (or d/l it from manufacturers website), or if running from your motherboard, d/l from Asus site (or you may need to make a driver floppy from the CD that came with your Asus board, their site should have instructions. You will need these drivers during the initial windows setup. When the computer starts to boot from the windows CD, you will see a message that says "press F6 if you need to load 3rd party drivers.." something like that. Press F6, then it will come to where it tells you to load your disc. If you don't do this, windows CD won't even see your RAID configured drives.
And ya, I do mean a hardware failure, in a RAID0, half the data goes to one drive and half to the other, that's why it's faster. Think of it as two pipes carrying water rather than one, your bucket will fill up faster . Either drive by ITSELF then is a paperweight with only half the data. There are also different RAIDS (1,2,3,4,5) some requiring even more hard drives. For a RAID1, you DON'T get the speed increase, because the SAME data goes to both drives, it's more secure, if one drive fails you still have all your data on the other. Or another RAID you could have 4 drives, half the data going to 2 drives, half to the other, then you get the speed AND security. Or you could even have 4 drives where the data is split up between them, but then if ANY of the 4 fails you lose it all. You have to pick what's good for you. I'd recommend two drives for a RAID0, and keep all your stuff backed up on your IDE drive. Personally I have two RAID0 arrays, one running from my motherboard, and one running from a controller card. Good luck with whatever you chose.