There are so many ATI cards available, in so many differing speeds, that I'm finding it rather confusing. I've even found some cards, supposedly identical, that have completely different coolers and slot requirements! 
What I need to know, specifically, is what cards will physically fit in my case. Additionally I would like to find out what cards are single slot, and which ones require additional power from the PSU.
What I'm trying to do is to narrow my search down, before I start deciding on capabilities/speed, if that makes sense. When I can find the smallest, least power hungry card, for my requirements then happy days!

What I need to know, specifically, is what cards will physically fit in my case. Additionally I would like to find out what cards are single slot, and which ones require additional power from the PSU.
What I'm trying to do is to narrow my search down, before I start deciding on capabilities/speed, if that makes sense. When I can find the smallest, least power hungry card, for my requirements then happy days!