Old SLR glass on new DSLR - should I even consider it?

Photography gurus...

I'm in the market to by a decent mid level DSLR and had shortlisted a Nikon D7000 or Canon 7D as the sort of camera to go for. In parallel I've found my late fathers old SLR camera gear and a little internet searching has suggested the lenses may have some quality and could potentially be used with adapters on a modern DSLR.

Lenses are...

• Tamron SP 35-80mm f/2.8-3.8 CF BBAR MC
• Komura 80-200mm f4.5 Telephoto Zoom
• Tamron 28mm F/2.5 ADAPTALL 2 lens

These lens are all screw thread and were partnered with a Pentax ESii.

Clearly I'd be manually focussing and I guess metering will be massively compromised, but could I still get quality results? 
The first two lenses seem well regarded on some sites, but am I going to lose so much quality that any outcomes will be far worse than buying new glass designed especially for DSLRs?

All advice gratefully received.

Beachcomber57