Having said that, with Windows 7 64 bit it basically means the two units I have had for years are no longer good for what I am doing.
I'll make a long story short and tell you to save your time looking on the Delorme threads or internet for help on how to make it work because it won't. Like others on here I finally broke down and am moving all my computers to Windows 7 64 bit which presents a problem for not only the Serial Emulator software but also the driver for the Earthmate in Windows 7. I have always had the Delorme Earthmate USB GPS puck and always been mostly good using the Delorme Serial Emulator except the flaky nature of the Serial Emulator stopping and having to reset or restart the entire computer. I wanted to append this thread with some new information. If you have any questions after perusing the past material please let us know, but IMHO the only option you have is to purchase a cheap puck online in order to resolve your issue.
This comes up quite often and it's a subject that has been covered pretty thoroughly, so hopefully you'll find the answers you need by reading the previous threads. I am just going to paste a couple of links for you here where you can read material already posted about this subject rather than reposting it. I am venturing a guess that the LT-20 is an older USB version that Delorme no longer manufactures as I was able to find references to it on their support website, but not much else in the way of useful information. The Delorme BT-20 works just fine and is the unit I and several other members use for their chase setup.
I haven't met one person on this forum yet who was successfully able to get the Delorme LT-40 to work with GPSGate, so don't beat yourself up about it. If you can purchase a separate cheap puck (the two that were mentioned here would be just fine) you should have the problem whipped.
pdf user manual found here XL-330 for the Tom Tom XL-330 you own for the terms 'NMEA' to determine if it offers an external data stream in the NMEA format and nothing came up, so I'm of the opinion that you wouldn't be able to use that for your setup (although I could be wrong).