I can totally feel your FRUSTRATION! I've been struggling with my own issues for the last couple of weeks (not exactly related to yours though!)
Anyway, I have one DNN site on reinvent also so I thought I'd throw in my 2 cents. I've been mainly happy with them, but there were a few things that bugged me, like the inability to create a support ticket for about the past year or so, and the fact that they want to charge me an extra fee for every little thing I ask them to do.
So for the new sites I am creating, I went with Infosaic. I have been very impressed with them so far, and the prices is pretty comparable to reinvent. If you are considering a move that might be an option.
Also, 512mb isn't very much ram. Ram is so cheap, why not bump it up. I never do any graphic or development with less than 2g ram. However, someone else had a good point that you might want to see what happens on a different computer before you spring for the extra bucks.
Hope things get worked out for you!
~B