I may have found a solution for the Maxtor / Windows 7 problem.
First, download from the Seagate site the Maxtor Manager application. Install it, and (this can't hurt) set it to run in Windows XP SP3 compatibility mode.
Then, if you are like me, over time you get your power cords and adaptors mixed up. The plug in teh back of the Mactor II and III series drives is a pretty universal one, so a lot of adapters will fit. YOU MUST USE A POWER ADAPTER WITH A DC OUTPUT OF 12.0 V / 3.0 AMPS.
run the Maxtor Manager app, then plug in your Maxtor drive. It does not matter if the drive is powered up before or after you plug it in. Once it is powered, two things will happen: the Maxtor Manager app will pop up and display the drive, and then Windows will run its Autoplay song and dance.
I was struggling for three days on this before I realized I had the wrong damn power adapter. If you have a lower output adapter, the drive will power up, spin and the light will come on, but it will NOT be recognized.
Hopefully this is the solution for some of you out there who, like me, have a rats nest of power cords collected from all the various drives and peripherals. Don't just select one that fits the plug!
Let me know if that works for anyone.