I have an automatic IP to the Cables infrastructure but I do have to run a ISP login script to get connected to the Internet. ( cables Co provides to different ISPs).

d/l tests vs the Cables Co. intrAnet were successfull and speeds as expected, and as fast as in WinXP (same PC).
but d/l tests vs the ISP (Internet) where at 50% of normal speeds.

Example from System Log :
* anon log[decaps_greptp_gre.c:407]: buffering packet 55280 (expecting 55279, lost or reordered
* anon log[decaps_greptp_gre.c:398]: discarding duplicate or old packet 58272 (expecting 58293)

And I have LOTS of those messages ( which will explain slowdown) .

I'm running Suse 10.1
Motorola SB4200 SurfBoard Cables Modem - Connected through USB.

Just to see if I understand you correctly, I think you have:
-a linux box, hooked to the internet via a modem that is connected to your box via USB wiring
-a LAN connection, which seems to work just fine (is it connected via the USB modem too?)

Have you checked:
-USB1 vs USB2? USB2 is about twice as fast as USB1, so this may explain the 50% mark you're seeing.
Check drivers, cables, modem, ...
-Is the modem capable of handling the maximum USB speed? If it isn't, your 50% speed may simply be caused by the fact that the modem simply isn't any faster.

I love some of the language here at LQ especially misspelled distros like Unbunto and Linix

I have edited my question. hope this clarifies..