2 accounts running on vista

What do you mean by "new data"? o.o

Making a new account would make new data on your computer that you (might) have to load when you start up, and (might) stick around even after you delete the account.

You can open more than one Windows account on Vista, but it has been patched so that you cannot open 2 instances of maple on the same machine, meaning that you would need a virtual machine to open a second Maplestory instance.

Hmm, really? That's sort of weird, how it's only patched for Vista. I guess I'll look into these virtual machines.