Everything new is actually well-forgotten old, that's what I think. Recently I had a desperate need to configure IIS 5.1 in our testing environment because of a pretty annoying error message:
HTTP 403.9 - Access Forbidden: Too many users are connected
The reason was quite simple: IIS 5.x by default has a number of connections limited to 10. Our lovely Micro$oft for sure would be happy if we would spend couple of additional quid and buy e.g. Server 2003 instead of good-old XP (if we really need unlimited connections so much). And this is a total rip-off in the middle of the day, right. And we don't like it VERY much. So... Always there is a solution, isn't it. ;-) And what is interesting: pretty legitimate in this case. So sorry for disappointing: we will not be hacking IIS today. No hardcore stuff like cracking, DLL injections, or binary files, etc. Everything is much much simpler.
For sure it was published somewhere before, but I still think this information may be useful for you.
Ok, so here is what you have to do if you want to enable unlimited number of connections for your IIS:
1. Go here [http://support.microsoft.com/...] and download Plugin MetaEdit and install it. Note: do not overwrite the new versions of DLLs with the old ones (you will be asked about it during the installation).
2. Go to: Control Panel --> Administrative Tools --> MetaEdit
3. Run MetaEdit (looks like RegEdit, isn't it?), go to the key LM/W3WSVC/MaxConnections and change the value from 10 to -1 (or 100000 if you feel better).
That's all folks! By the way, the MetaEdit is a very powerful tool which gives you full control over your IIS, so I strongly recommend you to play with it. But considering that it's Friday and the weather is (still) nice - maybe you'd better go out and take some fresh air. :)