The last couple of days I worked at a customer who was using Citrix Metaframe Presentation Server 3.0, it was the first time that I saw this product and I have to admit that I'm impressed. It enables user to start their everyday applications from within a browser environment. It was great to see that the web interface used ASP.Net and the nice thing is that you can completely customize it. If you run into problems, definitely check out the Citrix support site .
After developing the UI we deployed it to a production server on which a previous version of Metraframe was running as well so we didn't do an install but copied the directory with the files and created the necessary virtual directories. Everything worked except the ICA files were not correctly handled. It seemed that we still associate the ICA extension with the aspnet dll in IIS.
After installing ASP.Net, we however noticed that some of the users which were still using the Citrix 1.5, had problems logging into the web applications. They got a very strange error "error while encoding a gif file". It seems that while installing ASP.Net some userrights were removed. If you encounter this error, just give the anonymous user access to the nfuseicons directory