As I understand you, this should work just fine.

I do not anticipate any issues with 4.2.1

There is a nice sync utility that will automatically sync or create all the users it needs to sync the two systems up.
Basically it goes through all WP users, tries to match them with an existing vB user. If it can't, it makes a new vB account and syncs it.
Then it goes through all the left over vB users and does the same - tries to find a matching WP user and if not, makes a new WP acct automatically.

It's pretty sweet if i don't say so myself.

In the options, am I able to turn off all of the post syncing and just use the registration and user synch only?

I'm in the process of designing a new front page for my forum that will be done in WP. I want my vBulletin users (existing) to be able to comment on WP articles. If they're logged into vBulletin, I want them to automatically be logged into WP and visa versa - like an SSO only of sorts.

Am I able to adjust the settings in admincp to just allow for the vB>WP and WP>vb login feature?

Yes. You can use the registration and login sync without using the post sync.
There are three ways it will work:
Disable WP login and registration. Logging into vB will allow access to WP as well.
Disable vB login and registration. Logging into WP will allow access to vB as well.
Leave them both available. Logging in or registering in one, will handle the other.

I Bought the plugin, and when i activate it on wp and try to go to it's options,
it gives me the error
net::ERR_EMPTY_RESPONSE
the lite plugin was ok

what i need to do?

is possible to vbulletin 5???

I have not had the chance to test vb5. I would love to hear if anyone has.

I sent you a pm. Sorry you are having issues, but i'll be happy to look at it for you.

Great Plugin! testing in a BIG site.

Great, let me know how it goes!