Thanks for your posts 'sgoldswo', and welcome to the Forum!
The results of your research could definately explain why the first two posters in this thread were experiencing similar problems.
I wish you luck with Dell Technical Support although they will probably say that they only support their 5530 card with Vodafone SIM's, or words to that effect.
I suppose you could then try talking to Sony Ericsson directly, but I expect they would only refer you back to Dell... it might be worth a try though.
We will be interested to hear how you get on!