It will help to know (even if you direct him to other sites):

Computer type: (i.e. eMac, iMac)
Processor Speed: (relates to version)
OS X version: (some models can only go up to 10.1.5, others require at least 10.2.8; current version is 10.3.6)
Printer: (model and type - i.e. Brother 5040)
Scanner: (model and type - i.e. Epson 3170 Photo)
Printer Drivers: (version)
Scanner Drivers: (version)

Also, consider some of these sites:

MacNN

MacFixIt

Mac OSX Hints