Well, I'm not the expert that some others are but I have looked into it. Maybe I can offer a bit of info to save Dean some typing
Yes, if you exchange through MS, you are limited to the II properties in the World Passport Collection. Supposedly Disney has checked out all the ones that they offer and, for the most part, they are the top resorts. Seasons vary at II resorts just like
DVC. When you trade through MS, you trade a week at a DVC resort in a season comparable to the season you want at the II property -- I'm not sure if you'd have to exchange a Dream or Magic Season to get a platinum or red (or whatever the highest is called) II season; I don't think you'd ever have to exchange a Premier Season. For a low II resort season, you would trade Adventure season. If you want to know how many points it will "cost", look at the DVC
point charts to see what you'd have to give up for a studio, 1BR or 2BR for a week. You exchange a studio for a studio, a 2BR for a 2BR; because DVC is such a great trade, sometimes if you offer a studio, you may get a 1BR from a search but not that often.
You can trade any of the DVC resorts as long as you could book a ressie at that time. If your home resort is BWV, you can trade any week up to 11 months ahead and 7 months ahead for any of the other resorts. MS will figure all of this out for you and look for the least "expensive" week for the number of points you'd have to trade. You call MS and give them a few resorts to check and a range of dates. If they have a match, you can do the exchange then or they'll start a search for you so that if and when something comes up, you'll be notified that it's available and have 1 day to respond that you want it. If you refuse that resort/week, they remove that resort from the search. I think you can also set it up so that, MS will automatically do the exchange when it comes up without contacting you. I haven't been successful on any of my searches but I was being picky. Also, get your name on the search list way ahead of time (2 years); that way you'll be first in line if something comes up.
One thing that I discovered while calculating point costs, see if you can exchange Adventure season at HHI (much lower than other DVC resorts' Adventure season) - as long as you're within the 7 or 11 month window - you'd have to exchange for a II low season but you could get a very good deal.
A more flexible but riskier way to trade is to do an independent trade. As mentioned before
www.tug2.net is a great place to get info on many resorts. It's more than worth the $15/year. I listed BWV on the potential trade list and have had many responses. What is great about the private trades is that you can look to see which resorts people want to trade and the weeks they have to trade then contact them directly. Of course you have to be careful with who you trade with and what resort you trade for; there are not many like DVC. I have been offered a 2BR in exchange for a studio at BWV. It's great to own one of the best!
Right now I'm working on a trade with someone that will happen at the end of 2002. Plan ahead! Good luck!