Hi,
I've used these people for pc -parts
http://www.savastore.com/default.asp and they've been good and economical.. [img]style_emoticons/<#EMO_DIR#>/wink.gif[/img]
The best general advice is 'do your homework' a little before buying a drive - These days, you should get a multi-format (-/+ R, RW)drive, capable of writing to dual-layer (8.5gb) discs (usually only in +R) packed,posted inc VAT & delivery for under £40! (Most modern drives do all of the above, but read the spec carefully to be sure you're not buying the only one that doesn't [img]style_emoticons/<#EMO_DIR#>/thumbsup.gif[/img] )
As for fitting, as Wossie says, it's usually very straightforward,(assuming your O/S is XP) since most drives don't require any special drivers, but use the indigenous Microsoft ones.
Heres a basic guide
http://compreviews.about.com/od/tuto...s/DIYCDDVD.htm
P.s. The guides tend to make it sound harder than it is!!
Good luck