If you truly expect high traffic volumes then you had best test for that BEFORE you go live!!! I can't tell you the number of times I have seen clients try to scale up with a crappy database application and have it fail spectacularly. Two of those past clients of mine actually went out of business because they didn't get me on board to help before it was too late.

Speaking of which, asking the question like you did I can tell you with almost absolute certainty that you have ZERO chance of success here unless you get good professional help to review your application and assist with testing and improvements. SQL Server is AMAZINGLY GOOD at working well with bad design, bad schemas, bad maintenance, bad applications, poor hardware, etc. But high volume activity and concurrency requires that you do a LOT of things right. The good news is that (in my 15 years of consulting experience anyway) there are LOTS of things that are done wrong by companies that can provide incredible performance gains when fixed.