Hi,
Almost any firewire case and ATA (or PATA) hard drive will work fine! I would recommend spending a little more money on a firewire case - it generally means that it will use the better, more reliable oxford chipset (cheaper ones tend to use prolific).
You can also buy pre-made external hard drives by companies such as lacie. they can be slightly more expensive then building you own but for anybody technologically disadvantaged they maybe the go.
If you want to read the files on the PC;
• Format the hard drive as FAT32 (4GB file size limit <-- not much of a problem unless you play with video.
• Use a program such as macopener which will allow the pc to read the mac formated hard drive, the disadvantage of this is that it must be installed on every pc you want to read the hard drive on.
neil
Links - just to give you a general idea;
Hard Drive to put in firewire case;
http://www.epowermac.com.au/product.asp?nu...hFor=&PT_ID=162
Firewire Case;
http://www.epowermac.com.au/product.asp?nu...chFor=&PT_ID=70
Or Pre-Made;
http://www.epowermac.com.au/product.asp?nu...chFor=&PT_ID=75