import old users

[محروم.كوم]

hello*

We are currently running a self made forum with 1 table for the users (there are currently 50 000 users registered)* but it is getting slower and slower. so we decided to buy vbulletin 4.x* but is there a way to install vbulletin* and then import the existing users in one time?
We would like to keep the users* so we can provide a easy upgrade for them.

I suggest there is one mysql table for users in vbulletin too* can i easily write a querry that copies my data in the vbulletin users table?

thanks in advance __DEFINE_LIKE_SHARE__