Sharepoint 2007 uploading large files fails with http 404

Thanks for the quick response Maguz, had a look at article and it looks promising.
Have more pressing matters to deal so this will have to wait a couple of days.
Many thanks again,

Check the More Information Section of http://support.microsoft.com/kb/925083 if you've set the max upload already in Central Admin all you need to do is edit the web.config of the Virtual Directory you want to increas the upload to.

Add
<system.webServer><security><requestFiltering><requestLimits maxAllowedContentLength="209715200"/></requestFiltering></security></system.webServer>
In between the <Configuration> and </Configuration> tags where the maxAllowedContentLength is the size you want in bytes. 209715200=200MB

I have same problem and after I have added
<system.webServer><security><requestFiltering><requestLimits maxAllowedContentLength="209715200"/></requestFiltering></security></system.webServer>

Sharepoint sit gives "500 - Internal server error. There is a problem with the resource you are looking for, and it cannot be displayed."

Sorry guys I have been busy and this was a very low priority ... will be investigating it further and trying your responses in the next few days. Many Thanks

I made copies of the original web.config files and tried the solution in the Microsoft KB article and it threw a Server 500 error when loading the SharePoint site. I restored the originals and the site loaded fine. I'm not sure if I did something wrong. I edited in notepad and followed the instructions as listed. Anyone else have issues with that article?

When you add the maxAllowedContentLength section that is listed in the KB article to the web.config file under the virtual directory 80 you should add it at the end of the web.config file right before last </configuration> tag. Add the entire <system.webServer><security><requestFiltering><requestLimits maxAllowedContentLength="52428800"/></requestFiltering></security></system.webServer> part right before that last </configuration> tag and everything will load correctly. When I originally added it at the beginning, I received the same error as you described, but when I added it to the end, everything works fine and I am able to upload any file size under 50mb. If you need greated than 50, increase the maxAllowedContentLength value and make sure it matches and/or exceeds the value you set under SharePoint 3.0 Central Administration max upload size.

I have tried all in the above thread with no success on a 54 mb file. Is there any resetting or rebooting that needs to occur after these changes are made? I have tried an iisreset, but that is all.
I get a very fast response when I try to upload this file so I don't believe it to be a timeout issue.
My environment is SBS 2008 and SS 3.0. Any other ideas would be helpful.