OK, fixed it myself.
Since the 8.7.1025.2012 driver wasn't working I tried finding drivers on the Dell site. XPS 435T doesn't have any W8 drivers. Complicates things and I'm not sure that Dell supports W8 on this system.
My wife has an XPS 8500, basically just a newer version of the 435T. I know it also has a RealTek NIC on-board (she uses wireless and is running W8 too). So I looked at her XPS 8500 files as that system DOES have W8 files. Much to my surprise it had an older version 8 for the RealTek NIC. Version WHQL 8.2.612.2012 and although the file date is 6/12/12, it was created on 10/15/12. I install that driver and at first it too didn't work. However changing the ADVANCED setting for SPEED and DUPLEX to 1GB FULL seems to have solved the problems. Always connects immediately without problems.