Yeah temporarily turning it off to troubleshoot certain applications may be
necessary at times but I'd reenable it as soon as you are done testing
certain game and just add it to the list of exceptions.
Well I personally learned about this issue thanks to HL2 and steam not
liking it on my Vista computer.
I"m seeing alot more articles about in on the net now so I guess others are
starting to find out about it and yeah I think it gives Vista a bad game
since the few games I have had it on HL2,FEAR,AOE3 are some of the most
popular games so when someone trys to play them on Vista and they don't run
people automatically think Vista+games don't mix!
http://windowssecrets.com/2007/05/03/01-How-DEP-can-protect-your-PC
Although the DEP is supposed to display a message indicating when it has
shut down an errant program, some sources claim that the messages don't
always appear, and that DEP can sometimes even prevent programs (especially
installers) from launching. These sources go so far as to recommend turning
off DEP entirely.
Such advice is like throwing out the proverbial baby with the bathwater. If
you do have problems with applications that end abnormally or won't run, you
can always return to the Performance Options dialog to turn off DEP
temporarily as a test. This can help you get your software installed, for
example, if an installer won't run.
Overall, you're much better off making exceptions for a few problem programs
(and reporting the difficulty to the manufacturer) than shutting down DEP
entirely.
Finally, you should look at DEP as only one weapon in your security arsenal.
DEP adds an important layer of protection, but it isn't a reason to give up
your other security tools.