Systems Management

I haven't used Altiris in 3 years. However, their suite as of 3 years ago was superior to what SMS 2003 is now as far as software distribution, systems deployment (compared to SMS OSD), and ease of administration goes. If money not an object, and plan on heavy deployment activity, bank on Altiris.

I suspect SMS is more scalable, though...

If your environment is relatively simple then SMS 2003 isn't that bad. What I mean by simple is that it looks like the standard MS Active Directory environment with not a lot of different elements or requirements. Otherwise Altiris is probably the better solution. However, long term I think MS is always the best solution. Why? Because Altiris is probably better right now but in a year or 2 MS will have something different and better and I bet migrating from SMS to the new SMS would be easier than from another product. My response may add some confusion but it's something to think about!