I am looking for an inexpensive used desktop that has a PCI express slot and big enough power supply to support a decent graphics card with HDMI output, such as the ASUS nVidia GeForce 210 or similar. Using this for HD video mostly, no gaming.
Dell Optiplex 620's are Pentium D / Pentium 4 machines, and you can find them < $100 complete all day long with shipping all over the web. You can even find Optiplex 745's and 755's for around $175 complete too (Core 2 Duo machines, usually Core 2 6550 and 6750 processors, with a couple gigs of ram and 160gb hdds). Off lease liquidators are the place to find cheap systems.
Good find Mavroxur. Only issue with those older models is their pci-e slots are 1.0a not 2.0 and several boards dont support the newer cards. Also the biggest psu in those 745's is a 305w which is ok for what hes asking for but not much more.