Question : ADSL Upstream bottleneck?

Hi,

This is a newbie question, I think, but I couldn't find any educated answers myself.

Some background:
I got an ADSL 750/96Kb with network ECI modem on single home XP pro. I've installed bandwidth monitoring software: Telekomat .NET and PRTG free edition to collect some statistics.

The problem:
When the upstream is (over)loaded, the downstream suffers a TERRIBLE performance - so bad that many html pages simply time out in IE. I've measured the network load during a couple of days, and I clearly see the following results:
UPstream is always between 100 and 150K, and DOWNstream is NEVER above 250K, most of the time ~200K.
When UPstream is not intensively used, I get the desired downstream speed.

I've spoken to my ISP, and they told me that for each OVERUSED UPstream 1K, ADSL technology penalties me as much as >5K in DOWNstream; meaning that if I overload upstream by 50K, it'll resuse >250K from the downstream bandwidth!

The question:
1) Is what ISP sais correct? and if so why don't they limit the upstream on there side?
2) Is there any means (software/reg hack) to limit the upstream on my PC?

Note: K (Kilobit)

Answer : ADSL Upstream bottleneck?

" ALthough downstream speeds usualy are high, consumer grade dsl service often has an upstream cap of only 128K.  THis is about 3 times faster than a 56k dial up modem.  What's not generally well-known is that the upstream cap can also affect your downstream speed.  If you saturate the upstream by uploading, your down stream will drop to about teh same speed.  THIS IS DUE TO A WEAKNESS IN THE BASIC TCP INTERNET PROTOCOL, NOT DSL"

that's what I got word for work from Leo Laportes 2003 technology almanac
I have the same problem with my dsl.  If you do heavy uploading you might look to alternitives with your ISP.
GL
CHAD