We did used to have 'maintenance contracts', which gave you a year of free
updates, with one free upgrade guaranteed (i.e., if an upgrade didn't come
out in a year, you got the next one whenver it came out). This turne dout
to be an unbelievable hassle. When 5.0 came out, a whole bunch of
maintenance contract people were accidentally overlooked for a long long
time (we wouldn't have caught it in fact if these people didn't call
tocomplain).
We've since dropped the maintenace contract idea. It's too much work to
impliment, and the margin for error is high, which results in unsatisified
customers.
-Mike