Rotating vectors

Hi

I am currently developing a game. Where I have a vector3d let’s call it v:
[INDENT]v = (vx,vy,vz)
[/INDENT]let’s say I also have an angle w counterclockwise around the v vector.
Now i need to describe a vector t:
[INDENT]t = (tx,ty,tz)
[/INDENT]where t is 90degrees on v and t has the rotation w around v.
How do you find tx, ty, tz? (The length of t does not matter)

I have been trying to solve this and has come up with some strange results. If somebody can help me I would greatly appreciate it =)
If you have a link, that would be fine to =)