Microsoft SQL 2008 Cluster with replication
If you want to run read-only queries on the replication server - Have you thought about using database mirroring to a reporting server, and then using database snapshots to create a read-only copy? 

You'll need SQL Server Enterprise edition for asynchronous replication, and the other SQL Server will needed to be licensed as you're using it. You'd also need to test carefully, and be prepared for some latency.

I assume that you've performance tuned the database intensive queries?