>Granted, the UT has many features nicer than the newsgroups, but I find the way you display the threads not as nice (I'll try the time warp like you suggested). In the newsgroups using Outlook Newsreader (OE), you get, by default, the last 300 messages headers. This is not quite the same as I suggest, but does effectively do pretty much the same, because that many messages usually spans multiple days (and, of course, you can configure how many are downloaded).
As for displaying threads, they are two ways: mapped or listed. You can select that in your account setup.
When mapped, you can check your account setup to only display in collapsed mode. That'll give you what you want.