Lens and body are equally important, kinda silly saying they aren't.
However a quality lens should not lose its value over time if looked after properly.
I've been shooting on a 300D for almost 8 years and it has taken over 60 000 shots with only the shutter needing to be replaced. I have yet to come across a situation where I have needed a better camera so I have not 'upgraded' yet. It would have been nice to have a faster capture rate or higher res but not essential.
I shoot material for feature films, adverts, model portfolios etc. etc. I make a living manipulating images so I deal with them down to the level of individual pixels. What I'm getting at is you can still take great shots without spending a fortune and often all that extra cash is never utilized.
In this case I would suggest going for the 500 and spend the rest of your budget on a fairly decent set of lenses, a medium to wide-ish and a macro. Unless you plan on getting a job with National Geographic you are going to waste your money on anything more expensive. Don't get me wrong, I love having the best toys but when your final output is going to be what you show people at home or print yourself and web/email sized ones you upload you may as well spend the cash on something else. Next year there will be another range and your camera will be available for 3/4 the price you bought it for anyway
Think of your end format Vs your budget and work to that. Most of the time you won't be able to tell the difference between a great shot from a mid and top of the range DSLR regardless of the lens.