Not to hijack someone else's help line, but I've hit the exact same problem on two seperate computers(WinXP home and WinXP 64 Pro full updates on both). The sansa e280 isn't showing up as a drive at all. At least not with a standard mount point. Results of my own half hour's worth of explorations are as follows.
In folder view it shows up between Control Panel and Shared Documents.
It does not show up in Rbutil browse locations window.
The address bar calls it "My Computer\Sansa e280" with a subfolder "PPI NAND". "PPI NAND" has the standard MUSIC, PICTURES, sort of folders.
Device manager puts it under portable devices at "Location 0(Sansa e280)" Driver provided by microsoft dated 2/22/06 version 5.2.5326.4762
Firmware version PP5022AF-05.51-S301-02.18-S301.02.18A-D, (Build 32.10)
As stated, SANSAPATCHER cannot find any device.
Will explore more tonight.
EDIT: Feeling really really stupid. The problem is the USB setting. By default the device comes in MTP (Media Transfer Protocol) mode, required by evil people, like microsoft. To fix this, disconnect and turn on your e280, go to settings, USB modes, and select MSC (Mass Storage Class). Plug the device back in and Windows should let you know that it has detected a new mass storage device drive whatever. Problem solved.