I actually bought an Xbox for the Halo CE game, because friends had been pestering me about how good it was and an Xbox 360 for Halo 3. No regrets either after countless hours of fun gaming.
I have to mention the TimeSplitters series on the old PS2, because that series was not only fun but had some really good humour in them. The Story was weak in the first game true, but it definitely improved in TS2 and TS Future Perfect games, and the replay value was off the chart with the Challenges section and the Arcade League parts. Not to mention it had one of the earliest 'map-maker' add-ons too, which was fun messing around with.
They also had some of the best soundtracks ever. Too bad FreeRadical went under, I (and a helluva' lot of other people)was hoping for a TS4.