Terminal server serial COM port redirection and USB-to-Serial adapter

Several potential solutions come to mind:

One: Win7 UAC may be the culprit with COM access. Find a way to give the user access to Com. To diagnose this, first try to copy a local file (from computer console, not from tssession). Then try the same as an admin. Perhaps admin the user for a short period of time.

If this is the case, it might be fixed with a GPO in the vicinity of "Computer Configuration\Policies\Administrative Templates\System\". You want to allow users to use com and change its settings.

Two: You may share the printer on the tsclient, and use it on the server. To hide the local printer from network view, share it with "show in directory" off, and the share name ending in "$". Say "hiddenprint$" - shares ending with $ dont show in the explorer.

Then "copy file.prn \tsclient\hiddenprint$".

It is not possible to transmit audio from a client computer to a Windows 2003 Terminal server. It is not supported. I suppose there is a remote possibility that you could get Skype to accept a call and receive audio, but there is no possibility for you to transmit.

Windows 2008 R2 introduced a feature, to permit audio redirection, but it is not enabled on the terminal server by default. AFAIK, not linux-based thin client or remote desktop application supports sending audio. You need the 7.0 version of the remote desktop connector on Windows to support recording redirection. This isn't going to be available on an embedded version of XP service pack 2.

See this Microsoft document for setting it up audio recording redirection.

http://technet.microsoft.com/en-us/library/dd759231.aspx

terminal server can run now only one instance of skype

I highly doubt you will be able to get multiple copies of Skype running. I would be somewhat surprised if you could get a single connection running. AFAIK Skype is not officially support on a terminal server at all.