The speed differences between SATA and IDE, in my opinion, are negligible. While many people say that SATA gave them huge performance leaps, I just don't see how that is possible. The likelihood that you will see any major performance gains from a 12% increase in potential speed is next to none.
SATA still has some issues that IDE doesn't, and, until those problems are corrected, I will not be making the switch to SATA. The main issue that I have with SATA is that Windows still doesn't have built-in driver support for the different SATA buses. This means that you usually have to supply driver disks in order to install Windows to a SATA drive. I find it ironic that a person must use what is commonly thought of as a retired technology (floppy drives) in order to use the latest and greatest in drive technology. I don't have floppy drives on any of my systems, so I don't want to go through the hassle of installing one each time I want to install Windows to my system that has a SATA drive as its main drive.
It's true that SATA will most likely replace the IDE drives one day, but that day is very far off. If you check any online computer parts retailer, such as Newegg , you will see that most of the optical drives and harddrives are still running off of IDE channels. You will be very hard pressed to find any retailer selling more than a handful of drives that support SATA2 (yes, there is already a new SATA spec that already has products made for it).
I'd recommend that you just stay with IDE for the time being. While it's true that an IDE drive will one day become outdated, it is more likely that your drive will become rediculously and almost unusably small before its IDE connection will become obsolete.