Shalom,
You can get the Digital in and Out's if you want the new 8-outs come with the digital in and outs now. But if you want to send your tracks high end digtial then go get the SPIF's if not don't worry about it, your 8 outs will do the job just as good.
As far as the SMPTE card:
http://www.zzounds.com/item--AKAICM2TC
The SMPTE is used for time codeing. So if your using a PC your would mainly hook the SMPTE connector to the PC and have the PC and MPC communicate in a time code language, mainly it's just like midi just using the SMPTE option on a strick time code language.
What you have already is enough. But if your looking to dump your tracks down in a high end digital studio then go copp the SPIF board, if not then go make some beats and enjoy your MPC 2000.
one