Good choice with Giant there!!!

I got some pretty basic components on my Giant when I bought it but find that the best bits I have bought so far are:

SRAM components (already on bike to tell a lie) composite also
Sachs powerlink chain
Raceface bottom brackets/cranks/headset
Rockshox Pilot forks (I am poor) wouldn't mind some Marzocchi forks though!
DMR V8 Pedals
Club Roost grip shifts and saddle!!!!