Moving to Exchange 2007?

Ok situation is this
Need to upgrade Exchange 2000
Choice Available
1. Move to Exchange 2003
2. Moveto Exchange 2007

Move to Exchange 2003 - Pros & Cons
Pros ->
1.No need to change hardware, my existing server will happly take the load
2. No need to change the OS, exisitng Win2K3 will do the work( yeah.., I know what u are thinking, exchange 2000 on Win2K3? Yeah little secret will tell ya later :) )

Now Cons
1. One more new Server which may tie me up in a 64 Bit environment(if I go for Intel 64)
2. Need to additionally purchase Win2K3 64 bit version
3. May have to look for Office2K7 to utilize all the features of Exchange 2K7

Hmmmmm let me weigh all .....