Why don't you go for the Canon Eos 1D or wait until Canon release their new 1D cameras.
Personally, I'm not a big fan of the semi professional camera range.
I'm waiting until Nikon release their new D3hs and then it still depends how much the D2x will cost. The price of the D2x dropped with 1000€ last month
So, it will be the D3hs vs the D2x
To my mind, when you look at the D30's price you can better save up till you can afford the phenomenal 1Dn.
Nevertheless, the 30D is a good shooter
Good luck with it
CHeers