budget? (about 1/3 should be spend on the receiver typically)
number of speakers? (5.1, 7.1, 2 subs..etc)
where you want to purchase? (etailer? retailer? used?)
size of room? (to determine what type of speakers to use)
preferred speaker type? (satelite, bookshelf or floor stander)
as far as "first sound system, last purchase" you cannot expect a system to last forever. perhaps you may have it last for 10,15,20 years but its hard to call. electronics can die at any time, even if you buy high quality.
if you have a medium sized room (13x13 to 16x16) and are into satelite speakers for about $1500 you can get the exact same setup i have including all cables, wire, clips, etcetera.
pioneer vsx-30 receiver
klipsch quintet iv speakers (5.0)
klipsch 450w subwoofer
bananna clips for receiver, used binding posts on speakers
used monster cable speaker wire since it wasnt expensive and was good quality
but...you might have different tastes.
go to a local best buy or other such store which sells the equipment and go into the speaker rooms they have set up and see what speakers you like more! i would not suggest getting a home theater in a box (htib) set as you do not get what you pay for.