OK. Take away the optical drive and the revised cost is 388.92 AR. Now you have some options to consider.
MOTHERBOARD
You are correct – the mobo listed above does not have onboard graphics. I confused it with another – sorry. You have several good options to upgrade from the baseline listed above using the same good series of Gigabyte mobos. I did not see the one you listed – the GA-MA785GT-UD3H listed at newegg so I will let you plug it in.
GA-MA770T-UD3P(rev. 1.0) Baseline above $69.99
GIGABYTE GA-MA785G-UD3H $89.99
For the additional $20, you get a faster mobo, integrated graphics with HD 4200, and a slot for a second video card, but at one quarter speed. It uses older DDR2 memory – so if you select this option we will need to change the memory. DDR2 memory should not have a noticeable impact on your uses and might save you $20 or $30,
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
GA-MA790GPT-UD3H(rev. 1.0) $99.99
For the additional $10, you get an even faster mobo, integrated garaphics but with the slower HD 3300 version, and the slot for the second video card is one half speed.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Regarding the speed of the second slot, one quarter speed is more than enough to handle doubling the video card listed in baseline – and even some faster ones. One half speed will provide full performance to all but the top end enthusiast game cards.
All things considered, I favor the GA-MA785G-UD3H, unless you decide to go with the 5870 video cards below which might (don’t know) be slowed down a little in the second slot with only one quarter bandwidth, but am not sure if it best meets your preferences.
VIDEO CARDS
First, I just want to reiterate that the recommended 4670 video card will more than handle all of the uses you listed and allow some reasonable gaming. Here is a review that compares the generic 4670 with some faster cards – and shows you how the 4670 performs in game play
http://www.anandtech.com/video/showdoc.aspx?i=3405
The next step to consider is the 4770 – which is about 50% faster and is too new to be included in the above review. Here are some THG charts for comparison that tie into that article (note that 35 fps – frames per second – is the sweet spot – anything less starts affecting the appearance and anything more you won’t notice – but it is nice to have some overhead for growth) :
http://www.tomshardware.com/charts/gaming-graphics-char...
And here is a decent 4770 card
MSI R4770 CYCLONE Radeon HD 4770 512MB 128-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail $94.99 AR
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
The primray reason this is a large $40 jump in price (besides being a lot better performing card) is simply because the 4570 includes a great rebate and the 4770 is new and in high demand and discounts are just not being offered.
The next two steps should be the new cards covered in the following review which I include to let you see what the cards can do and if you want to spend the extra money:
http://www.tomshardware.com/reviews/radeon-hd-5770,2446...
Note that if you move up to these cards, while your power supply can easily handle one card you would probably need to upgrade it before going Crossfire with 2 cards. The earlier cards should work in Crossfire with a 600w PSU.
ASUS EAH5750/2DIS/1GD5 Radeon HD 5750 1GB 128-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail $129.99
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
MSI R5770-PM2D1G Radeon HD 5770 (Juniper XT) 1GB 128-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail $159.99
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
With the video card – you have to just go with your preferences since the baseline card clearly meets all of your stated needs. The video card might meet all or most of them too, so you still might elect to try that option as it is simple to add the card later. But it certainly would be nice to have room to accommodate growth if you think you might need more later.
Revised total with high end options of both mobo and video card: $523.92