My friends and I visited prague for a week 2 years ago and we stayed at the Barcelo Praha hotel. The accomodations were rather nice and it wasn't very expensive. Here's the contact info.
Barcelo Praha
street NA Strzi No. 32
Prague 4 KCR CZECH REPUBLIC
tel: 420-2-61103111
fax: 420-2-41442023
enjoy your stay in Praha
also, here's a website with photos and stuff:
http://www.euro-hotel-discounts.com/.../PRG_BARC.html