Hi,
This is possible as I've had to do similar (I've got a bitmap in memory and wanted to save it (see the http://www.vb-world.net/ubb/Forum1/HTML/015425.html thread). Bascially you have to do the following;

Assuming you have your picture in a picture box you can do it one of two ways

(a) - Rough and ready, StretchBlt your picture from it's current picture box into another picture box but scaled to be the size in pixels that you want. Then you can do a SavePicture thingy on the picture box
(b) - Scarey API.
Create a Memory DC (compatible with your picturebox)
Stretchblt your image into it to the scale that you want
Convert the MemoryDC into a DeviceIndependantBitmap
Save the Memory location for this DIB as a file

Either will work, but (a)'s far easier, but it depends on exactly how you want your application to work

cheers

Andy