You need to get out of Warsaw :)
Smoke starts coming out of my ears if I go more than a few miles from the end of the metro.
Seriously, I'll look out for Dino.
It's biedronka that have the market in Warsaw, that and Carrefour Express. A nice alternative is the coop. They've got big stores in Żoliborz, Marymont and Bielany.
Spar are quite posh. They bought Piotr i Paweł.