Master Degree or Job?
Generally, the latest/greatest degree you have is considered the most important. 

Technology does change quickly, but principles change less rapidly. So if you have a good degree, it won't matter so much that technology changes. If you know the principles, then you can learn new technologies and more advanced concepts. If you only know how to use some specific set of tool, then you might have trouble as technology evolves.

In general, a masters degree may help you get a better initial job, especially if you want to do something specialised, such as computer graphics, security or data mining, but once you have a job your experience will matter most, not your grades or degree.