truncate in transaction blocks read access

I have a million-row table (two text columns of ~25 characters each plus two integers, one of which is PK) that is
replacedevery week.  Since I'm doing it on a live system, it's run inside a transaction.  This is the only time the
tableis modified; all other access is read-only. 

I wanted to use "truncate table" for efficiency, to avoid vacuum and index bloat, etc.  But when I do "truncate" inside
atransaction, all clients are blocked from read until the entire transaction is complete.  If I switch to "delete from
...",it's slower, but other clients can continue to use the old data until the transaction commits. 

The only work-around I've thought of is to create a brand new table, populate it and index it, then start a transaction
thatdrops the old table and renames the new one. 

Any thoughts?

Thanks,
Craig