First off, please excuse my ignorance..

OK, so I have a Bianchi Advantage that I really like as my daily commuter, seriously fredicated but it suits my needs well. Well, it is getting to the point that I want to upgrade my SRAM X.4 rear derailleur and options seem rather limited.

Would upgrading to 10 speeds be simply a matter of replacing the cassette, rear der and shifter? Will a 10 speed derailleur fit on the existing hub that is now holding an 8 speed cassette?

Any constructive advice is greatly appreciated!