Yep, no doubt about what's required, new wheels and tyres. Stevenb's suggestion looks good, worth checking weights compared to what you have now. Like a lot of wheels, Aksiums are good value and pretty too but are not overly light at 1855g per pair (2008 models, previous versions are 140g heavier). It doesn't sound a lot, but on wheels light weight really makes a difference. I would be tempted to go for the Ultegra's if available for £190 a pair.
In between, Fulcrum Racing 5's have been well recieved too.
My tyre choice would be Michelin Pro-Race 2's, cheap from Parkers.