It's difficult to tell all of what you may get without going through all of the intervening updates, but the couple of main fixes in the A09 BIOS have been referenced in Microsoft Knowledge Base articles.

1. If you're running WinXP or Win2K and have a LAN and a multiple USB port setup, or some other "multiple network" configuration, network setup will create a "bridge" to prevent "looping" between the two or more "networks." Some systems don't handle this very well. Relatively few people have setups that contain more than one "net," but it's not always obvious when it does happen so some may have looping nets and not know it.

2. Some PCs, especially portables, have had a lot of problems with "sleep mode" in their power management systems, especially when a USB mouse is used and/or when USB devices share a port. Microsoft warns that "moving the (USB) mouse" while the machine is "entering sleep mode or other reduced power mode" may cause the machine to fail to recognize the mouse, or some other USB device(s), when you "wake up" the machine. The conventional fix is just to turn off the "power saving options."

I'd say it's still pretty much a personal choice unless you've had one of these problems. You may want to review the fixes in earlier updates, assuming the descriptions are still available, since Dell apparently assumes you've read them all. (i.e. they only tell you the incremental changes, so you have to read them all in order to get the full picture.)

John