@Greogr
Indeed. 2008 R2 is stable and an improvement over 2003. Not to mention that 2003 cannot run the newer IE versions, which are an improvement in both speed and security over IE 8 (highest version that will run on 2003). Of course you can use FF/Chrome, but just saying . . .
That said, 2012 R2 is a big improvement purely from a performance perspective. The problem is trying to wrangle it into a well-behaved TS environment.