Hard Drive Selection
If you know anything about physics or engineering, then you know that moving parts produce friction and wear, and a faster spinning platter (the part that holds the data and spins) means more friction, and therefore more wear on your drive. Of course the faster it spins the faster it can read data from the platter. So what can you do? well again you backup your data as much as possible and you get the fastest spinning drive money can buy (which is 7200RPM for ATA devices (the sort you are buying) and 15000RPM for SCSI and some Serial ATA devices (you might get Serial ATA, that depends on your motherboard)). So look for a "7200RPM" label on the drive you're thinking of getting, it's important!
The "buffer" I'm referring to is the transfer buffer that temporarily stores data to read from or write to the hard drive. The reason for this is that the bus (data channel between the hard drive and the motherboard) can only handle so much information at a time, and it takes a long time for the data to be found and retrieved from a platter (random seek time), so it takes a big chunk of the requested data and stores it in a very fast data buffer to be sent at the bus's convenience. So with a larger buffer you can queue more data for transfer over the bus without having to keep sending requests to slowly find more data from the platters. Some newer drives come with as much as 8MB of buffer capacity, but it is more common to see 2 or 4MB. Usually a drive with a large amount will use that as a selling point and print it on the box/website, otherwise you can assume it has a 2/4MB buffer. My advice is to find one with as much as you can afford.
Now for the transfer rates you're going to need to do some searching, the best way to find these numbers is to go to the manufacturer's website and look at specification sheet for the model you're looking to buy (actually this is the best way to get all the information I've talked about so far). One thing to look out for is that you may read something that says 133MB/s or ATA/133 or SATA150 or 150MB/s, and these are not the numbers you are looking for, those numbers describe the bus connecting the hard drive to the motherboard, and are theoretical peak numbers, which tell us virtually nothing. Also, if you are buying a Maxtor, don't bother looking up actual transfer rates, as Maxtor is apparently afraid to release such information.