If money is tight, the BD windsor is tough to beat at $600 (the Nashbar runs $750). Personally I'd buy the Surly LHT but in all honesty I can't say it's worth 2x as much.
If you want to do this inexpensively, just upgrade the shifting system on your bike. You can post your questions in the mechanics and/or touring forums and you'll get a lot of advice. You'll need a triple, a new chain, and probably a new rear derailleur. It will cost you less than a new bike. This nashbar triple for example runs $60:
http://www.nashbar.com/bikes/Product...9#ReviewHeader. It has a steel 22 tooth inner (which is a good thing on a small chainring) and a 22 running on a 26 rear will give you a nice low first gear. You may need a few tools but you will learn how to work on your bike which is a good thing to do if you're going touring.
Edit: I did a bit of research on the Panasonic DX 1000. This looks more like a sports touring bike than a true touring bike. The chain stays don't look that long (which can be a pain for heel clearance). You may just be better off buying the Windsor.