Thank you very much for the many replies and the information!
I think I'll basically proceed like
Li Shenron suggested; I have decided to give the group very complete charsheets that may explain some of the most ardent questions that might pop up for themselves.
As to the basic set, I'll certainly check it out, though I am not sure if I'll end up taking it, since I have the old 3.0 starter set floating around here, and that one was of virtually no help to me until now.
FATDRAGONGAMES said:
I am not intending to start a flame war here, but you might want to consider trying the Castles & Crusades Quickstart rules that are available for FREE on the Troll Lord Games website. These will give your players an intro to fantasy RPGs without any cost and since it is OGL they'll never know the difference.
Oh, far from it!

I myself am a C&C player, and would usually use that system, or maybe even OD&D, which is my home system. Now, the adventure, which is part of the Blackmoor MMRPG, is built on d20 rules, and so, instead of having to do conversion work, I decided it would be best to simply use the ruleset the module was written for.
Now, tomorrow's the day of the game, let's hope that I can polish my rusty d20 knowledge in the meantime...
Again, thank you very much, everyone!