userport.sys by Tomas Franzon (available with source code)
Windows NT 3.x/4.x/Win2000/XP driver for direct I/O port access

userport.sys is a driver which enables direct hardware I/O port
access. Because TwinAVR uses direct hardware access for speed
reasons, the program doesn't work under NT systems without a
special driver such as userport.sys.
userport.sys was tested successsfull under both Windows XP with SP1
and SP2. If You don't get success it might be You forgot to push
the button "Update" after changes before pushing "start".

Note that under Windows 3.x (yes, TwinAVR can run under Windows 3.1),
Windows 9x and ME you don't need a special driver. Under these
systems the direct hardware port access is not restricted in any way.

How to use userport.sys:
1.  Copy UserPort.sys to %windir%\system32\drivers 
2.  Run UserPort.exe to set the port range you wish to open.
    Standard LPT addresses are:
    LPT1: $378 ($378 - $37A)
    LPT2: $278 ($278 - $27A)
    LPT3: $3BC ($3BC - $3BE)
2b. Push "Update" button once if You made changes
3.  Push "Start" button
4.  Now You can run TwinAVR
5.  If You like You can now push "Stop" in UserPort.exe

The only drawback is that you are opening a security hole on your
system that could be exploited by malicious programs. Therefore, open
the I/O port range only that you need access to. With LPT ports only
there should be no security risk.
The full userport package including sources You will find under:
http://www.embeddedtronics.com/public/Electronics/minidaq/userport/UserPort.zip
and with Google when using the keywords +"userport" +"Tomas Franzon".