Easiest way which is still low impact probably is to produce a staging table on the 2000 server with an identity and the data that has to be transferred.
The v7 server has an identical table but with an int for the ID field.
Thev7 calls a stored proc on 2000 with its last ID via a linked server or remote server (could even use replication for this but I wouldn't advise it). This sp returns the next 500 say (recs) which the v7 server inserts into its staging table.
The v7 server can then do whatever it wishes with the data (may have a status field on the recs to say they have been processed.
This has very little impact on the 2000 server as it's production processes just have to get data into the staging table - doesn't matter if the v7 server is down.
If the v7 server has to be restored then it will automatically recover the data from the v2000 server. You will have to cater for the 2000 server being restored though.