Building a cheap media/work desktop

[_HighVoltage_]

I need some help/advice coming up with a cheap system to run at home. I like to work from my couch and right now I've connected my laptop to my 23 inch monitor, but as you can imagine the cables are annoying.

Budget is under $500.

I am considering getting a small barebones PC, but they seem to like versatility - have to get an extra optical drive, can't really pick CPU or GPU options, etc...

Something I find very tempting is the Lenovo C50 all-in-one, because that way I can connect my existing 23 inch to the Lenovo and run 2 screens which would be sweet.

But let's consider what else I have as choice - maybe build it myself. Criteria:
- Intel only. i3 and above.
- running Windows 8/8.1
- 6GB RAM seems plenty at this point.
- 500GB and maybe a small SSD for the OS
- for now the Intel 4400 seems enough, but I'd like to have the option to add a dedicated PCI-E GPU.

Does this seem possible for less than $500? What motherboard should I look for?

 

[h-p]

I'm thinking getting myself a used Lenovo Thinkcentre M81 for htpc use. Should be around $300.

 

[_HighVoltage_]

Dell just put on sale the Alienware Alpha for $399. That's very tempting, I can't really see any downsides to it.

I'll also need new speakers since my JBLs finally started to give up the ghost after 9 years of use. I'll post in the audio forum for that.