Posted on usenet "Can't recommend Slingbox" contemplating worst possible review at Amazon where we purchased the unit.
There are a lot of people who bought Slingboxes and gave up on using them. They are definitely not user friendly.
But once you get them tweaked they are sweet.
It took me a couple of weeks of tweaking. Then I changed my entire setup by putting my DSL modem in bridge (opposite of the factory settings) and I don't have anymore problems. Before that I was trying to open ports, forward ports, dmz, and etc with a wide range of results.
I have not tried a HAVA brand "place shifting" unit but it may be easier to configure. Maybe you can find one locally with a 30 day back guarantee or something so you can return it if you get the same problems. I think there are some other companies making "place shifting" units also, but the big two are SlingMedia and HAVA.
Your best resource is to go the Sling Community website. Some of those guys are geniuses when it comes to this stuff. Give them all your hardware, software, location, ISP info and I bet they will be able to help you.
Good luck!