I've had good luck with the cheap DLink DGS-2205 "Green" Gb switches in my Sonos network. My network looks like this, with 4 more wireless Sonos units too:
Code
                             Cable Modem
                                  |
                            WRT54GS router (wireless disabled)
                                  |
                             1Gb switch
                                  |
      -----------------------------------------------------------
      |                           |                 |           |
  1Gb switch                 1Gb switch        1Gb switch   HD-Homerun
      |                           |                 |
  -----------------     -----------------     ------------
  |          |    |     |     |  |      |     |     |    |
WRT160N(AP) PC  Sonos  X360  BD HDDVD  DVR  Sonos  WHS  Mac
                  |
                 DVR

The cheaper HP pro-switches don't like Sonos either, but the $30 DLink's work great smile



Living room: DSP5000.3
WFH Office: M33
Bedroom: P200ZQ