using old film SLR lenses with a DSLR camera body

I am new to the DSLR scene, having purchased a sony a390 a few weeks ago.

My dad has an old 35mm film SLR camera, with a variety of lenses (including zoom/macro and wide angle). I believe that these lenses have a Pentax K bayonet mount.

Can these old lenses be used with a new DSLR camera, and if so which one?

I have had a look at the pentax website, and it would seem to suggest that they could be used with the Pentax K-X DSLR. Does anyone have any experience with doing this kind of thing? Would anyone suggest a different camera body?

I appreciate that due to crop factor, the focal distances on the old lenses would not be directly comparable when used on a DSLR camera.

Thanks in advance.