Oh - and be wary of components from high end racing bikes. Standard bike components are designed to be tough, good value, reliable and long lasting. High end racing stuff is designed partly to get every last ounce of performance (and damn value, component lifetime, etc) and partly to appeal to high-end bike freaks will to spend money to get technological "ultimates" - even if they don't translate into performance.
A good example of this would be Campagnolo's 11 speed (per chainring - so 22 speed on a dual ring bike) powertrain. The thing gears cost more (they need to be made of super hard metal) wear out faster, and need the most exotic tools. A good tool to remove a normal chain costs £15. For the Campag 11 speed... £150. Oh - and you should use a seperate peening tool. I don't know how much that it is. Or even what peening is. I should probably find out - especially as I am stuck inside today - but the word is rather off-putting.
10 speed powertrains aren't quite that tricky, but they're still more neurotic and faster wearing than 8 or 9 speed.