I just finished upgrading from Vista 32 to Win 7-64. The OS runs smoothly, but I've had few problems. I'll explain:
Windows installs most of the drivers you'll need. It doesn't install the bluetooth drivers or the ricoh memory stick drivers (though it installs other ricoh drivers). The only problem that Windows might have is with the Ricoh. just download the 64 bit version from your driver support page. Eventually windows will get annoyed enough and give you a download directly from the Dell website, but I suggest installing it before this happens.
In addition to the Ricoh and Bluetooth drivers, I suggest you install the IDT Audio driver (but wait until after other updates are installed - for some reason it didn't work right away). The sound is better and not as blaringly loud as the MS codec. I also suggest Dell Support (which automatically discovers your Tag), and Alps Touch Pad (This will help you selections options such as disabling the touchpad when a USB mouse is connected).
Really, I've had no software or driver problems. My device manager is clear of any conflicts or driver issues.
I have the TSST TS-T633A Slot Driver. Before upgrading, I updated the the firmware for the drive from DS300 (or whatever it was) to DW20 (I believe). I don't know if the firmware is the issue, but after the disc drive is in dis-use for some time (30min or more) and you press the eject button, it freezes up the system, closes the network connection, and you can't use the drive until a restart.