ETL Architecture - Streaming Data Into An OLTP

Interested in feedback from the SQL grand wizards (and would-be wizards) that haunt these forums.

Let's say you need to constantly stream data into an OLTP system. We are talking multiple level hierarchies totaling upwards of 300 MB a day spread out not unlike a typical human sleep cycle (lower data during off-peak, still 24/7 requirements). All data originates from virtual machines running proprietary algorithms. The VM/data capture infrastructure needs to be massively scalable, meaning that incoming data is going to become more and more frequent and involve many different flat record formats.

The data has tremendous value when viewed both historically as well as in real-time (95% of real-time access will be read-only). The database infrastructure is in it's infancy now and I'm trying to develop a growth plan that can meet the needs of the business as the data requirements grow. I have no doubt that the system will need to work with multiple terabytes of data within a year.

Current database environment is a single server composed of a Dell PowerEdge 2950 (Intel Quad Core 5355, 16 GB RAM, 2 x 73 GB 15K RPM SAS ) with an attached Dell PowerVault MD1000 (15 x 300 GB 10K RPM SAS in RAID 5+0 [2x7] w/hot spare) running Win 2k3 64-bit and SQL Server 2005 x64 Standard, 1-CPU.

I am interested in answering the following questions:

Based on the scaling requirements of the data capture and subsequent ETL, what transmission method would you find most favorable? For instance, we are weighing direct database writes via stored procedures for all VM systems versus establishing processes to collect, aggregate and stream CSVs into a specialized ETL environment running SSIS packages that load data and then call SQL Stored procedures to scrub and prepare for production import. The data will require scrub routines that need access to current production data, so distributing the core data structures to multiple ETL processing systems would be expensive and undesireable.
Cost is very important to the overall solution design. In terms of database infrastructure, how would you maximize business value while keeping cost as low as possible? For instance, do you think there is more value in an ACTIVE/ACTIVE cluster (2 x CPU licenses) where one system acts as ETL and the other as OLTP or would you favor replication of production data from ETL to OLTP or (vice-versa). With the second scenario, am I mistaken in thinking we could get away with a Server/CAL licensing model for the ETL server?.
Are there any third party tools that I should research that would greatly aid me here?


I appreciate all feedback, criticism, and thoughts.

Best Regards,

Shane