I just thought I'd share my experience since I didn't find too much information out there when I was looking a little while back. I bought an Inspiron 9400 a little while back with a Core Duo T2300. Like any good moder, I tore down the system pretty soon after I got the system and it looked like my options were pretty good for upgrades. I've now taken the first step and upgraded the CPU to a t7400 The upgrade couldn't have gone smoother. I updated the BIOS to the latest, unplugged the system and removed the battery and tore down the system. For the curious, there are guides out there on replacing the video cards that are written much better than I could do. The only difference is I removed the CPU and chipset heat pipe instead of the video card. The socket on mine is fairly standard for the boards that do have sockets. You use a strait blade screw driver to turn the locking cam until the CPU is unlocked, remove it, insert the new CPU, and relock the socket. My system booted and ran fine, so of course the first thing I do is post this in the forums I think the power management on the Core 2 is better than the core it replaced. Speed step seems to be working better and Windows seems to think it gets a tad better battery life out of the CPU. If you are going to do this, you need to make sure you get the 667MHz FSB CPU, not the 800MHz version used on Santa Rosa platforms. It should be a socket M part, not a socket P. The problem is they can easily be confused so make sure you are certain of the specs.
