well actually CCNA and Microsoft Certifications are two different packages which are vendor specific. CCNA is geared towards Cisco's knowledge and experience in networking particularly using their product line such as router and switches, while Microsoft's exams are more to there software product line such Operating Systems, etc. Both provide you with credentials that can be used in the IT working field. however each is not a prerequisite of the other and each can be taken even without passing the other.
by the way, congratulations on passing the mcp exam
yes you can definitely do CCNA. just make sure that you are able to get a hands on experience on Cisco's routers and switches and be able to do configurations. you could also try and wait till the site's Cisco Lab is up as it would offer great ranges of goodies to choose from