Is upgrading a G4 easy?
=>if you by G4 mean the tower, very easy
Can I buy extra internal harddrives later and have them easily work like they would if I bought them from apple or do I have to buy other devices that I'm unaware of?
=>buy any har disk format it with the disk ututility included with your mac and you are all set.
Is installing an internal superdrive hard to do?
=>You have to pry lose the bezel so it some more steps than a harddisk but there are instrucions on the net (
www.xlr8yourmac.com and others)
I've been using a laptop for so long, I haven't had to deal with this stuff, well on a mac, ever.
Anything that you can't do unless you buy from apple?
=>Not really but some of the graphical cards are only aviable on BTO (like the ATI 9600) and some features of the cards that are both BTO and retail has some differences.
I know that you have to get the bluetooth internal thing from apple and it can't be installed later.
Anything like that?
Thanks for the help.