Derek's point about using a different account for "admin" and for "normal use" is very valid. However, if you're the technical user, it gets annoying having to switch back and forth. And, of course, some software pretty much requires that you be administrator on your local box.
I don't think that Windows security is "dumb" as much as it is "unused," at least when you're in an AD domain (like I've set up here at home). Of course, you can't do what you really ought to unless you're running XP Pro rather than XP Home for your workstations.
The one area where Windows really falls down at is as an FTP server. Windows FTP server is WAY too easily exploited - so much so that I stopped using it, and specifically worked up a Linux box (and believe me, I'm barely able to do anything on a Linux server in terms of configuration) to replace it. One of the best choices I ever made. I also use the Linux server as a mail front-end...although it moved behind a different server (via folks called NoIP.com), and now, I've reduced spam to next to nothing between their front end and the Linux box in front of the Exchange server. But ultimately, there is that Exchange Server...I actually *LIKE* Exchange. I make use of the Public Folders extensively - for example, for the fantasybball e-mail address you guys use. Doing things that way allows me to get rid of any vendor who decides to distribute the address I give him. It's a little disconcerting to a vendor when they ask me my e-mail address, and I tell them it's their_company_name@joev.com. And if I get junk mail...guess who distributed the address. I then deactivate the address, and the vendor loses any future business.
I also have VPN connections set up with Skander and Caleb, so we're actually one big private network through the internet. Makes it easy to share files, music, etc. They've even got the ability to print to my color laser.
The downside is that there's a bit of work to make sure it stays up, and works as appropriate. Then again, that's part of the computer-geek side of me...messing with the network is kind of fun. At least sometimes.