I have read that many people like the Epson V700 scanners, but I was wondering what the main differences between the V500 and V700 is other than dimensions of it?
The V500 is cheaper than the V700.
What other scanner is recommended for $500 or less.

The V700 can scan every thing from medium format to 8x10 slides. The V500 can only go as far as medium format. Depending on what your planning to scan they are both good. You pay extra for the larger film with the V700. If not the v500 is perfectly fine.
Other scanners below $500? Try the microtek M1 which seems to go head to head with the V700. If going used look for a epson 4990. Used prices on these are ridiculous (alsmost $400 on ebay) so look local. Non of these is better than a dedicated 35mm scanner if thats all your planning to do

The largest format I have is medium format right now, so it sounds like the V500 is a good way to go for now. Thanks for the help.