Linked servers on SQL Server 2008 R2 through linked tables in MS-Access?
You should be able to get away with this by creating views in SQL Server that are effectively wrappers for tables in the linked server. You will of course have to deal with the extra layer of security configuration for the linked server, thus ensuring that the Access users are connecting to the external data with the proper credentials (whether it be something per-user, or just a global set of credentials that's used for everybody accessing the FoxPro data).

Keep a close eye on performance, since Access is going to be generating queries meant for SQL Server, and it tends to be a bit chatty to begin with. SQL Server is then going to generate queries for fetching the data from FoxPro. With that many layers of query generation, performance could be a crapshoot for large tables, and it'll be pretty difficult to diagnose or improve it.

If the FoxPro data is mostly static historic data, then I'd recommend bringing it into SQL Server. If there's still read/write activity happening, then you'll have to either settle for the linked server approach, or periodically refreshing the data in SQL Server via SSIS or some other ETL.