This would definitely be a good move and with the DBA background a nice compliment. I might be a tad biased though:) As previously stated I would check out the opportunties and demand in your area, but I don't believe you will have any issues tracking down any jobs, especially since you also possess the DBA knowledge.

With MS BI you have lots of different areas you can look at with the database engine, SSIS, SSRS (and Report Builder), SSAS (and Data Mining), Excel (and PowerPivot), ProClarity (still around), PerformancePoint, SharePoint. SharePoint is a key strategy for Microsoft, so you will definitely need to have an understanding of that product as well.

Pick one area at a time and read up on a book, do some of the Microsoft Virtual Labs, watch some webcasts, etc. and then move on to the next product. Having knowledge of more than one is always a plus.

Let me know if you have any further or specific questions and I would be more than happy to help you out in anyway that I can.