Windows 7 on D630 with 57xx Gigabit Controller

My D630 works well under Win7 Pro (32 bit) using the latest drivers, with one exception.  The Broadcom NetXtreme 57xx Gigabit Controller only operates at about 10% efficiency under Win7 compared to XP.  Using InternetFrog I can clock downloads around 13 Mpbs under XP, and similarly with my Dell wireless connection under XP or Win7.  But under Win7 the Broadcom RJ45 LAN connection only gets about 0.15 Mbps downloads, dog slow.  :(

I even tried using the latest Broadcom Vista/Win7 driver dated 10/1812, version 15.4.0.17, but the RJ45 download performance does not improve.  Upload performance is unaffected and works well all-around, regardless of O/S or network interface selected.  I see others mentioning this same issue with Win7 and the 57xx Gigabit Controller on the net and in these Dell forums, but never a viable solution identified.

I have also tried Win7 Pro 64 bit, Win 7 Ultimate 32 bit, changing Ethernet cables, upgrading to the latest D630 A18 BIOS and fiddling with the network Speed/Duplex setting, nothing seems to help.  There is lots of chatter on Dell and Microsoft forums that Windows 7 is temperamental with older NIC equipment, some people can get things to work with a variety of techniques, others (like me) cannot no matter what is tried.  Dell just says the D630 is not supported for Windows 7, yet some people report it does work (after lots of random trial and error effort).

Any ideas, anyone?