http://www.users.bigpond.com/steven_cooper/dnd/dnd-revised.htm
http://opengamingfoundation.org/srd.html 3.0
wizards.com/d20 3.5
The creation of blindsence in 3.5 means that rouges can get sneak attacks on more things
Devil and demons got a lot meaner in 3.5.
Vrocks hold their own in melee now, but lost the Mass Charm
Dragons had their CR's bumped across the board. still no built dragons in the MM.
Golem's had their magic immunity severly weakened.
Improved grapple really changes the combat dynamic.
To attack with a light weapon in grapple, you have to oppose grapple checks, succeed and then attack at -4
Power attack's 2 for 1 trade off on 2handed in 3.5 is rife for overuse/abuse.
Web works 'like' it used to in Basic, 1E and 2E
Lighning bolt is unneededly weakened
Conjurations, even attack spells, rarly give spell resitance.
All stats have Animal buffs, those got busted down to 1 minute a level and set at +4 bonus. This was done because players would use empowered and maximised buffs to keep Item slots open at higher levels of play when they were 1d4+1 1/hour a level. I can only assume this was done because the rpga DM's have to follow the rules and not change them.
your horse is now 10 feet fat.