Will be installing an AM3+ board w/965BE into this case today (along with a Cooler Master GX 450W PSU). I'm not going to overclock at first, but in about another month as I transition this to my main system, I probably will. I know there are some monster heatsinks and such out there, but I think quite a few won't fit in this case.
Anyone with experience with the larger heatsinks such as the ProlimaTechs or Zalman 9900s in this case?
Also, will adding the optional additional fans (side, front, top) to this case make a good difference on cooling? (such as fans at which positions net the best results).
It's a good case at a good price. It comes with just 1 fan so you'll probably want to add a 2nd fan (suggest 120mm rear exhaust) to go with the included 120mm front intake fan. That's plenty to start out and you can always add extra fans later. If you know you'll want to add fans look at the 4-pack options for just a few more $$ than the single fans.
For CPU coolers - you probably don't want to add one that costs more than the case itself.
160mm tall CPU coolers are known to fit and a great cooler at a great price is CM Hyper 212+ 158.5mm tall $30 plus $10 rebate. It can use an optional 2nd 120mm fan for a future push/pull cooler upgrade.