To disagree with Beggar, you can't look at the activity level in the eng-tips forum. Most posts are in the private Solid Edge newsgroup hosted on the UGS servers. You need to be SE maintenance subscribers to get access. That has all the traffic and you get direct answers from SE support many times, unlike here. That is where the traffic is and is hidden from public eyes.
Also, this has more traffic, not necessarily because it is a better program, but because SWX did a better marketing job and has a larger market share. More seats = more users with questions = more posts to any and all forums.
The question of longevity of SE is just misunderstandings about the corporate umbrella that SE is under. SE and UG just got bought out by private investors from EDS. This is very good news for both CAD packages because EDS only advertised its IT services, never its products. As its own company, you will start seeing marketting ads for SE and UG and therefore I think they'll start regaining market share from SWX.
To get back on topic. The only difference between SWX and SE is workflow. I like tell the software what I want to accomplish and it gives me step-by-step on how to get there. This is SE's workflow. With SWX, you start with a sketch and tell the program what to make of the sketch (and in my case only to be yelled at that I didn't include enough info to actually create that feature.) Other than that, you SE and SWX are the same, feature-for-feature, realizing that there is more than one way to skin a cat. Just because you do it one way in one CAD package doesn't mean it can't be done in another simply because you don't do it the same way.
If you're on a tight budget, I'd also look at Alibre Design.
--Scott
For some pleasure reading, try FAQ731-376