Well, the dsl-320t is a dsl modem, not a router. See this link for more details on the difference between the two:
http://www.computing.net/networking/wwwboard/forum/4060.html
That being said, I vastly prefer the cisco 678 as a DSL modem. Myself and two of my friends have used them for the past 5 years, and they truly are rock solid (never had one fail unexpectedly, or act 'weird'). You can pick one up for $25 (+S&H) from a place I have used before, here: http://dsl-warehouse.com/product_info.php?products_id=79&language=1
Keep in mind that if you arent using QWest, it might not work out of the box (in fact, you should call your DSL provider to make sure that it will work at all). If you need to configure it, configuration has to be done via serial console cable (at least initially, it has a web UI but this is disabled by default).
Another data point is that "good" is totally dependent on your DSL line. Some modems perform better than others under adverse (aka noisy phone lines, ones with a low SNR ratio) conditions, while others preform really well on clean lines better than others. I've heard that the speedstream 5200 and 516v6 series are modems that perform well under a variety of different lines (and the are easy to set up than the cisco 678, as well). But that is strictly hearsay on my part, as I haven't used them personally.
One last thing: if your P2P app suddenly stopped working, but all of your other internet applications still work (i.e. IM, web surfing, etc), your ISP (or some other upstream entity) may be filtering your network traffic and denying any P2P traffic that you are sending/receiving (just as an example, the cable internet provider Comcast has been doing this for the past few months).
If you are using uTorrent, one quick fix might be to turn on protocol encryption:
Options->Preferences->Bittorrent
Change outgoing protocol encryption to "Enabled" and uncheck the "Accept incoming legacy connections" checkbox.
Hope this helps.