Richard, I'm NOT in computer sales, but I am a software programmer and have built several pc's, so I have a little experience with them. Here's my opinion...

First, Dell is a great brand of PC. I recommend you purchase from a dealer like Dell where you can get a 3 year in-home warranty as opposed to having an acquaintance build you one cheap (but is hard to get serviced).

Second, while the 4550 is a great PC, you have to look at how you plan to use it. If you're only planning on using it for Internet usage and light-weight applications, you don't need the most powerful CPU or RAM. Also, for Internet usage, a powerful video card isn't necessary.

That being said, if you're primary use for the PC is Internet usage, I think the 2350 is a better deal because it's $250 cheaper and the main difference is the CPU, RAM, and video card are just slightly less powerful than the 4550.

On the other hand, it seems like I've seen you mention running CAD programs. If you plan on running them on this PC, I suggest you purchase the most powerful PC you can afford. CAD programs tend to be CPU, RAM, and video intensive, so you'll need the extra horsepower. Plus, if you ever buy a new CAD program, it will only be more of a resource hog than your current one, and you won't want to have to buy a new PC to run it, so the little extra cash now could save you money in the future.

Hope this helps,
Will