PATA and IDE are the same thing,they are actually PC IDE PATA HDDs. PATA is actually an old name for it SATA HDD's are in a league of they're own. They use am Serial connector rather than a Parallel connector hence the name. SATA came about as a faster way to transport data. In lab conditions an SATA HDD can transfer up to 150MB/s, PATA HDD's are what we all have seen since the dawn of computing, the large connectors that plug into the back and have speeds 33, 66, 100, 133. The Ultra-ATA's have 133MB/s rate but you will never see these results it's just what it is capable of handling.

SATA-II which came out just recently can transfer up to 300MB/s but real world results are obviously much less. ALL motherboard come with IDE controllers and most now have SATA controllers, but if you want fast SATA is the ay to go and the fastest is SATA in RAID-0.

The RPM is the amount of times the head of the hard disk spins. The faster the head the faster the computer and retreive stuff.

If you wish to upgrade hard disk, but which type to find at ebay, newegg ...

1. confirm what the connector of present hard disk. for example: ibm thinkpad T40. this is mahine produced on 2003. Most of these laptops use PATA(IDE).

2. So you can buy 2.5' PATA 80G 120G 250G hard disk. Recommend WD, Seagate, Fujitsu.

3. if you are using IBM ThinkPad T60, it uses SATA