hi, i wanted to add (not replace) a 1TB hard drive to my computer as the one i am using is constantly full and is a family computer. i am using a Power Mac G5, with these specs: Model Name: Power Mac G5 Model Identifier: PowerMac7,3 Processor Name: PowerPC G5 (2.2) Processor Speed: 2 GHz Number Of CPUs: 2 L2 Cache (per CPU): 512 KB Memory: 1 GB Bus Speed: 1 GHz Boot ROM Version: 5.1.8f7 Serial Number: CK425JC4QPM an apple webpage (http://support.apple.com/kb/HT1305?viewlocale=en_UK) specified measurements and hard drive types, but i can find no mention of those measurements on any hard drive shop webpages i find, including amazon. so my questions are: 1. can i use just about any SATA hard drive?/ are they more or less standardized in terms of size? 2. is there a problem with buying a preowned one, because they are very expensive otherwise? thanks a lot, and please bear in mind i have very little knowledge of macs.