The last thing I would do is put off getting certified until the .Net exams are released. I wouldn't expect to see exams for .Net for at least 6 months after the official release of .Net, and that isn't expected until late fall at the earliest.
Also, I would imagine that the .Net exams will be much more difficult than the current exams because Microsoft is working hard at making the exams more challenging. For instance, the Solutions Architecture is really tough in relation to older exams because the methodology has evolved. I highly recommend you consider getting certified now; the .Net certification is just too far away to consider at the moment.
This was first published in March 2001