If you're on a budget, go with some of the olderA-mount Minolta glass, I have a 350 and use the 50mm prime and macro, good lenses. They do make a difference. And although I have a Canon mainly for product shots, I still use the 350 when I just want to grab a camera and go, the battery life in the 350 is amazing. A great camera!
Given that you will likely have to upgrade lenses to take advantage of a high resolution sensor, lenses are probably the ones to upgrade first. Are there any specific issues you are trying to solve with an upgrade?
Good thread, going the upgrade lens route myself, like stated above I have also heard newer bodies will showcase the faults of poor lenes, the way I look at it, you'll need em both eventually, so why not get better quality pics now and then upgrade the body down the road.