The image looks straight (vertical nearest the middle of the frame is upright) but your shot is angled up, meaning the verticals are heading towards convergence.
You need to use the perspective crop tool. IIRC on CS2 it's as follows:
Use the crop tool from the tool menu to select the whole image. Make sure the "perspective" box is checked on the main toolbar at the top.
Use the mouse to drag the corners of the image. To correct converging verticals drag the top corners horizontally towards the image centre; this will stretch the top edge and align the verticals.
This will also make the image look a little squashed in the vertical axis, so you want to stretch it by a few percent when you've finished![]()