I bought a new Dell e1505 couple mons ago with the 7300. The Inspiron 6400 is identical to 1505, except they offer the 7300 or X1400 (1505 only had X1300). From what I read the X1400 is faster, but don't know if it's very much faster. I didn't buy it to game with (see below), but for the heck of it I loaded some games. Here are my impressions of the 7300 with 1gig memory & CoreDuo @ 1.86mhz and 1280x800 LCD running at native resolution: (note no AA on)
Older Games:
Call of Duty & Call of Duty-United Offensive - maxed out with 8x AF runs smooth as glass.
Newer Games:
Call of Duty 2 - kinda slow & choppy with DX9 and medium settings. DX7 with settings maxed out & 4x AF smooth as glass (this is essentially same as original COD).
Far Cry - With medium settings & 2x AF runs VERY well, much better than I thought.
Half Life 2 - maxed setting runs smooth, but there are pauses at times which I cannot fix (this happened on my desktop when I first go it - upgrading ram to 1.5gig cured it)
Quake 4 - medium settings, no AF very smooth, although there may be times it'll slow down some, but nothing you can't play through.
Don't buy these to play the newest games - you'll be sorely disappointed if you try with everything maxed. But with low settings it'll do OK. I imagine the x1400 would do marginally better, but I don't think it'll be drastic.