It's more about the hard drive than the interface. Let's say the IDE drive has a 4 millisecond (mS) seek time and my SATA has 8 mS. The IDE wins the usual benchmarks. Change the drive specs and the winners and losers change.
I have an IBM desktop from the pre-dual core era. Thinkcenter
Intel 4, 3.2Gz. XP Prof
The board has IDE connectors. Would I benefit from a gain in performance if I installed a card that allows for a sata drive?
oh and I will be installing Win 7