Windows XP and 330 - It does not fly like the vision I was s

I cannot get my compaq Evo n115 with windows XP to recognise my Pentax 330 ...............

Looking like $400 down the drain

Any ideas

Only the very basics - check all the cables, re-install the software, get any updates or patches for the software via the internet, try any helpline number (as a last resort because of the cost!).
Every time you get a computer problem it's a bit of a steep learning curve sorting it out, but I guess something gets learnt every time!
One last thought - if you are using some other application before you try to download images from the camera it might be grabbing and holding on to the port. Try restarting the computer and downloading from the camera before anything else.

Another thought - if you used a card reader to download the pictures it might be more convenient than using the camera.