I picked the MSI low profile HD 5670 myself for my slim Desktop Dell Optiplex 745
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127523&Tpk=hd%205670%20low%20profile
one issue I had though was the height and length of card were okay
but the width (side to side) was too wide to clear my CPU heatsink and fan
you will need the PCI-E x 16 socket to be about three inches or more away from the PCI-E
I managed to cut the dual fan assembly in half with a pair of cutters
and make it into a single fan so it would fit
There goes my warranty LOL
So as long as you have the clearance around the sides of the PCIE slot
you should be fine
they should have the dimensions of card on Newegg or AMD site
I like the Hd 5670
it can play BioShock2 at highest settings at 1920x1080
it can play Crysis warhead at 1920x1080 at gamer settings
it doesn need an external powerconnector
it was picked by Toms as best $75 card for May
if you can find a HD 6670 low profile that is a little better for about $100
also a Gt 240 is decent though the HD 5670 outperforms it