I'll post the changes I've made. I haven't taken into account the performance of the program. Most surely it can be optimized quite a lot. Seeing your programming experience, I'm sure you're capable of it

1) Two important constants:
VB Code:
  1. Public Const PI = 3.1415927

  2. Public Const HALFPI = 1.5707963

2) I've extended your Star UDT:
VB Code:
  1. Public Type Star

  2.     Phase As Double

  3.     Colour As wRGB

  4.     DestX As Long

  5.     DestY As Long

  6.     Speed As Double

  7.     LumCap As Long

  8.     x As Long

  9.     y As Long

  10. [b]    dist As Long

  11.     ang As Double[/b]

  12. End Type
Dist and ang will hold the distance and angle of the star, as seen from the center of the picture box (polar coordinates). These will be derived from x and y.

3) Code modifications to make the starfield actually rotate
VB Code:
  1. 'COMMENT TO NOT SPIN!

  2.             '.x = CentreX + Cos(Angle * (3.1415926 / 180)) * (CentreX - .x)

  3.             '.y = CentreY + Sin(Angle * (3.1415926 / 180)) * (CentreY - .y)

  4.             

  5.             .dist = Sqr((CentreX - .x) * (CentreX - .x) + (CentreY - .y) * (CentreY - .y))

  6.             .ang = Arctan2(CDbl(CentreY - .y), CDbl(CentreX - .x))

  7.             .x = CentreX + Cos(.ang + Angle * (PI / 180)) * .dist

  8.             .y = CentreY + Sin(.ang + Angle * (PI / 180)) * .dist

  9.         'COMMENT TO NOT SPIN!
Dist is derived by simply applying Pythagoras.
Ang is derived by a modified Atn function (named Arctan2) (see modification 4)
X and Y are calculated accordingly.
Tip: to reverse the spinning you need to swap either the result of the Cosine or the Sine, not both.

4) The modified Atn function:
VB Code:
  1. Public Function Arctan2(y As Double, x As Double) As Double

  2.     If x = 0 Then

  3.         If y > 0 Then

  4.             Arctan2 = HALFPI

  5.         Else

  6.             Arctan2 = -HALFPI

  7.         End If

  8.     ElseIf x > 0 Then

  9.         Arctan2 = Atn(y / x)

  10.     Else

  11.         If y < 0 Then

  12.             Arctan2 = Atn(y / x) - PI

  13.         Else

  14.             Arctan2 = Atn(y / x) + PI

  15.         End If

  16.     End If

  17.  
  18. End Function
The advantage of this way is that, if you pass x and y separately (instead of y/x), you'll get the angle in the right quadrant of your coordinate system (instead of only the first or fourth quadrant).