and i am purchasing a new 160GB Hard drive,
which type do i buy? IDE or SATA?
and another question...
Well to better answer your question you can get both. It doesn't matter as they are two different types of connections. So you can have 2 HD's on one IDE channel, a hard drive on each SATA port for a total of 4 drives unless you have 4 SATA ports then obviously you can have more.
However the biggest thing about SATA is that it is a 150mb/sec transfer rate whereas IDE only has a max of 133mb/sec and at that you need to make sure you're buying an ATA133 drive for it to transfer that fast.
Also SATA of course has it's famous 10,000RPM hard drives, but are fairly expensive. Those things haul ***.