IMO, you will see faster load/read/write times over IDE with using a SATA drive. IDE caps out at a theoretical maximum transfer speed of 133 MB/ps, where SATA starts at 150MB/ps or 1.5GB/ps. There is also SATA II that supports up to 3GB/ps.
SATA is serial, IDE is parallel.
Both are based off of ATA technology.
IDE is more limited by devices supported. One channel supports two devices which must be set master/slave. SATA is always the master and more ports can usually be fit on a mobo.
However, as mentioned, if only to save money, move to SATA once your IDE drive dies.
But then again, if you have some money to burn, get 2-80GB SATA drives and put them in RAID0 for a significant hard drive performance gain.