The JVC camera shoots HDV, where the P2 cards from an HVX-200 shoot DVCPROHD, which is the better of the two formats. You’ll want to convert the HDV camera’s footage to DVCPROHD and edit in a DVCPROHD sequence. Hopefully, both cameras have shot the same frame rate… if not you have yet another problem. 24fps all or 30fps…
I’ve an article in the current issue of the COW magazine about how to transfer the HDV footage to DVCPROHD so it conforms to the the footage shot by the HVX. course all this is moot if the shoots have been DV and not HD… if they are DV, the formats will match. Both cameras are capable of shooting DV as well as the HD formats they shoot. FCP 5.1.2 should capture the material just fine from the JVC camera, and the P2 material from the other also works just fine, but you’ll want to match the formats, and DVCPROHD would be my choice here.
Jerry