Hmmmm, tricky. For on-site installation, which inevitably includes some making up of boxings or maybe even making window boards, etc I'd go for a straight cutter (1/2in diameter), a round-over bit w/bearing (1/8 or 1/4in radius), a chamfer bit w/bearing (45 degrees), a trim bit w/bottom bearing (1/2 to 3/4in diameter) and a coving bit w/bearing (3/8in radius). That lot will allow you to make-up a lot of stuff. Rebates can always be worked by using a straight bit and the router's fence (assuming you have a European-style plunge router which will come with a side fence as standard). If you intend to do a lot of copy routing I'd recommend getting a top bearing template trimmer as soon as funds permit.
Last edited by Phil P; 10-07-2010 at 12:24 PM.