I don't know if this will help, but as a comparison, we have a few upload processes written in Cold Fusion that takes various files (including CSV, Excel, and Text) and inserts/updates records on the fly in one of our SQL Server databases, and the records inserted/updated are in the upper limits of 100,000 per file.
Couple things to think about:
1) Make sure that you have identified a long time-out period in your ASP script, since that will affect the processing time, meaning that if you don't increase the time threshold in your script, than the script will probably time out.
2) Make sure that you set your SQL Server for a longer time-out period for receiving requests.
Q: Are you planning on running this process in the background, like as a Scheduled Task -or- is this is a script you'll be running from the web browser?