1) XEON means nothing. Quad-core is useful for #2 but #1 has just a brand name. (which is better to drive on I4 in Orlando? Chevy or Ford? without mention of other specs ... the brand is not of any use, right?)
2) Vicidial installs Asterisk. So both servers will usually be Vicidial (and both will usually have asterisk, although that's not required)
3) Every time I hear "Sip trunking" I assume someone is about to be "sold" by a really good salesperson on a CONTRACT for VOIP which is just plain outrageous. If you haven't signed, DON'T. VOIP telephone service is not an "annual contract" item. Anyone trying to sell you that could just as easily be trying to sell you an auto-warranty or home-security system. Not kidding. Back off and get a professional Vicidial consultation (hourly, don't get any other service with it, just a straight up "tell us what's real here" without getting any other service from the consultant. You will likely save several thousand dollars. At the very least, be sure your VOIP (Telco, Carrier, whatever you want to call them) is NOT IN ANY WAY linked to your Internet service. And be sure you get your VOIP through the internet (not some sort of funky local contracted T1, those ALWAYS turn out to be a ripoff!). If you keep them separate, you're really just getting internet from someone (lots of competition, so pricing is ... competitive). Then you get your VOIP from anyone who will sell it to you over the net. And if they piss you off (poor quality, overcharging), you flip 'em the bird and switch to another service. Since they are not your ISP, they have NO control over you. I'd tell you how many business owners I've heard talked into $2k/month contracts but were told something entirely different. Then the first invoice lands and all heck breaks loose. Solidly locked contract, you signed it. No matter what the "Nice Salesperson" said. NEVER contract for VOIP beyond "month to month".
4) Search this forum for phrases like "db dialer web" (the three main roles a server can have) and you may land on posts like this one:
viewtopic.php?f=2&t=32303Happy Hunting