Tokyo Marui M4 RIS. Everything is original except the PEQ box, battery, upper body, and the stock spring was replaced with a 100. Originally bought in March 2004 from Softair Depot, when that was around. Got kills with it at today's game in Jan 2009.
Longevity is what makes Maruis so amazing. If you want to be in the sport for a while, than buy Marui.
Also my Marui AK-47 I have had since September 2005, also from Softair Depot, has never been in the shop and it has had thousands of rounds fired through it. It is 100% original. No upgrades, mods, nothing done to it, and still fires beautifully, after 70+ scrims over the past 3 years. No joke. That AEG is amazing.