I was planning on going the same route with my rims when I purchased new rubber. Would have like 205/50 ZR17 for the front tires but it's an uncommon size and about $30-$40 more per tire so I stuck with 225/45 ZR17 all the way around. You can feel it in the steering from a dead stop, but once the car is rolling, steering gets a little easier. I was tight for cash too at the time, I could go back later and buy another set of those tires, dismount the front and have two complete sets them. They are a directional tire.
These are the tires I bought: Maxxis MA-Z1 Victra. Got a good deal from a local shop in Whitby called Tool Tyme, owner's name is Ian. Only thing is he doesn't install so I went up to 2nd time around in North Oshawa to install them. I've dealt with them in the past & Ian recommended them too. There is another member here who has also bought rims & tires from 2nd time around.
http://www.tyrereviews.co.uk/Tyre/Maxxi ... Victra.htm