I finally got my old 9700 video card (in analogue mode)to work at native res (1680x1050) with my Belinea 102035w 20" WS LCD and official CAT drivers,problem was there was no option for that res in CCC panel or monitor tab,even after I installed the inf monitor driver files in WinXP(this is on my backup PC).
Funny thing was I had no problem when using Omega drivers,the 1680x1050 was always there for VGA input.
I tried the usual things list all resolutions etc...checked refresh rate(even tried changing that).
Anyway the fix was kind of weird,I had to connect my DVI cable as well ,suddenly I had 1680x1050 res pop up as an option,I made sure everything was set at 1680x1050 res then disconnected the DVI cable and let the VGA cable take over,that fixed my 1680x1050 problem.
If you are wondering why I did not use the DVI cable on my 9700 as main input ,thats because its used on my Nvidia 7800gt card which is on my main PC.