Well seems like parts are about 30% more so yeah you probably could afford a i7 pretty easily. A decent starter level i7 build is probably around $900 USD so you would just need to add the soundcard and extra hdd space. However if you don't think you really need it you could spend a little less on a c2q or c2d build. But unless intel was planning on coming out with better lga775 chips later you wouldn't really be able to upgrade because i7 is skt1366 and the next chips will be that and lga1156. Also even if Intel did come out with better 775 chips they probably won't be as fast as i7. So yeah you will probably end up having to upgrade everything.
In America you would start off at around
base of core i7
motherboard - $200
i7 920 - $290
3gb ddr3 ram - $75
base of c2q
motherboard - $80
q9400 - $230
4gb ddr2 ram - $40
base of c2d
motherboard - $80
e5200 - $73
4gb ddr2 ram - $40
You could of course spend more (especially on the dual cores) but thats a starting point.
In America you would start off at around
base of core i7
motherboard - $200
i7 920 - $290
3gb ddr3 ram - $75
base of c2q
motherboard - $80
q9400 - $230
4gb ddr2 ram - $40
base of c2d
motherboard - $80
e5200 - $73
4gb ddr2 ram - $40
You could of course spend more (especially on the dual cores) but thats a starting point.