RICKDUDE  Pity you didn't check out Bookends alongside Sente. I'm always looking for comparisons of these two leading bibliographic programs. Looks like the most recent comparative review was a year ago, and a lot has happened since then.   
(Version 5.7.3)

RICKDUDE  An update on my earlier comment:

I went ahead and ordered the upgrade on November 19th. It was shipped on December 2nd, and arrived here in Japan about two weeks after that; that's about a month from order to receipt. People not in the US might want to get the upgrade now rather than wait until they actually need it! The price (upgrading from a Version 4 CD) was $12.95 plus $8.95 s&h, as Alsoft had promised.

It's now on DVD and way faster than before. Apparently it works with all Macs except those introduced in October 2008.  
(Version 4.1.1)

RICKDUDE  DiskWarrior's web site is uninformative, and I was left under the impression that I was going to have to pay full upgrade price to go from my version 4 CD to the version 4 DVD to start up my new-ish Intel Mac (NOT the newest ones launched in October 2008; I bought in September 2008). I was getting ready to say goodbye to DiskWarrior, after using it for a number of years.

But I emailed their Customer Service just to make sure, and in their (very prompt) reply they said that, although the web site (even the ordering system) says the upgrade price is $49.95, once they have confirmed that you're an owner of version 4, they lower the price to $12.95 plus shipping.

It's a pity they don't make this more obvious. Alsoft does seem to be at odds with the times but it seems clear they're not the gougers some of us had suspected. I've no way of knowing whether this is true, but perhaps they're a small company spending all their time working on the software, raising their heads only when an email comes in from a customer, or something along those lines. In any case, as the owner of a few Macs, it's my experience that it's always best to have the latest version of DW at hand. Note that 4.1.1 does seem to be pretty fast, too.  
(Version 4.1.1)

RICKDUDE  This is very, very good. I don't really know what I'm doing, but was able to make a semi-competent screencast in quite a short time.  
(Version 1.2.1)