I use SMF software and I absolutely LOVE it. Here are some links:
http://www.simplemachines.org/ - The Official Home Page.
http://mods.simplemachines.org/index.php - OFFICIAL Mods Page, with LOTS and LOTS of mods.
http://www.smfhacks.com/topten.html - Here is a SMF Hacks Page, Lots of good stuff.
http://www.smfarcade.net/index.php - If you want an ARCADE for your site.
http://www.forumflashgames.com/smf/index.php - Hundreds of Flash games for SMF Arcade.
SMF is FREE however they do offer tech support in their AWESOME forums:
http://www.simplemachines.org/community/ I always get my questions answered fast.
SMF also offers a PAID service or they call it "Charter Service":
http://www.simplemachines.org/charter/ They offer LOADs of support and will even install it for you and upgrade for you as you request. All for just $49.99 a year but it is totally optional and even I don't use there paid service.
I use SMF for the largest dialysis message board on the internet and we have been featured on CNN and a few industry magazines. I have thought about changing to a paid forum but I am really happy with SMF and all of it's features.
Rossman orignally gave me the heads up about SMF and I am sure glad he did. Rossman also turned me on to Liquidweb:
http://www.liquidweb.com/ for my VPS and DAMN I am glad I listened, I have found it's best to just listen to Rossman for advice on ATOT.
To OP:
Just stick with SMF, you'll be glad you did. I thought about vB but I am very happy with SMF. I may give vB a try one day, but right now I'm happy.
- Epoman