GPU for media streaming PC

[pcu]

So I am in the planning process of building something like, Powerful media HTPC for less then $500

No interest in gaming here. Just trying to figure out what I need to stream 1080p video. I want to send video via HDMI to my son HT-CT150 soundbar then from that to my panasonic st30 plasma.

Also does it make sense to buy a motherboard with integrated graphics AND get a seperate graphics card as well?

For CPU I am thinking something in the vain of

Intel Core i3-2125 Sandy Bridge 3.3GHz LGA 1155 65W Dual-Core Desktop Processor Intel HD Graphics 3000 BX80623I32125
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115093


Intel Core i3-2105 Sandy Bridge 3.1GHz LGA 1155 65W Dual-Core Desktop Processor Intel HD Graphics 3000 BX80623I32105
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115090

Intel Core i3-540 Clarkdale 3.06GHz LGA 1156 73W Dual-Core Desktop Processor Intel HD Graphics BX80616I3540
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115221

Still have a bunch of research to do and not really sure what my processing requirements are gonna be so I don't know if any of those are over/under powered for what I am looking for.

As for GPU's I really am new to this and so I have almost no idea how to gauge what is over/under powered for my needs. All I really know is that I need it to ahve HDMI

MSI N450GTS-MD1GD3 GeForce GTS 450 (Fermi) 1GB 128-bit DDR3 PCI Express 2.0 x16 HDCP Ready Video Card
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127606

 

[pcu]

One thing I am confused about is HMDI port. I see the graphics cards I am looking at have an HDMI out. Some of the motherboards also have them. Am I to assumer that if I go with a separate GPU that i would not need a motherboard with HDMI out? I am assuming those motherboards have HDMI out if your intention is to have integrated graphics and thus you would not have a separate HDMI on the GPU card.