I'm more of an Intel person, myself, but if you pick up a cheap monitor also listed on the first page here, this turns out to be a pretty decent system for cheap! ( Probably want to upgrade the video card if you want to do any serious gaming ).

Wonder how this would do as a media pc?

#2, probably not bad if you were going to watch TV/movies on the monitor you buy, but you probably can't do HD without buying a vid card. Double check, but I'd be amazed if this had an HDMI output you could run to an HD set.

That being said, you could add a card with an HDMI output for probably $50 or less. It wouldn't be a great gaming card, but if you're really just looking to do HDTV it would be fine.

The CPU would be plenty powerful for HD.

not a bad deal for everyday computer

of course if you do upgrade the video card you'll also have to upgrade the power supply

whats the size of the monitor?
specs etc?

Monitor is sold separately.

lacks expansion slots.
"EXPANSION SLOTS:
• 1 PCI Express x1 (occupied)(24)
• 1 PCI Express x16 (occupied)(24)"
Which I think is a lie (http://www.newegg.com/Product/ShowImage.aspx?CurImage=83-107-991-10.jpg&Image=83-107-991-02.jpg%2c83-107-991-03.jpg%2c83-107-991-04.jpg%2c83-107-991-05.jpg%2c83-107-991-06.jpg%2c83-107-991-07.jpg%2c83-107-991-08.jpg%2c83-107-991-09.jpg%2c83-107-991-10.jpg%2c83-107-991-12.jpg&S7ImageFlag=0&WaterMark=1&Item=N82E16883107991&Depa=3&Description=HP%20Pavilion%20Slimline%20S5120F%20(NP187AA%23ABA)%20Athlon%20X2%207750(2.7GHz)%204GB%20DDR2%20NVIDIA%20GeForce%206150%20SE)

"(24) Power supply upgrade may be required for graphics card upgrade, check with graphics card supplier."