"Is it possible to SLI/CF Intel Graphics"
I don't quite understand that as SLI (Nvidia) and Crossfire (ATI) are not Intel Graphics, however, the only way you can use two different discrete cards + the processor GPU (Intel) is if your motherboard supports Hydralogix and Virtu. If I understand your question correctly, if the board supports SLI/CF, then yes you can SLI or CF two cards and use Virtu (Hydralogix won't be needed. Hydralogix is used only to support two different discrete cards like both ATI and an Nvidia together, or a GTX 460 and a 8800GT or something + you can use Hydralogix and Virtu together if you needed to use these cards with the processor GPU).
IMHO, if you're using SLI (or CF), plus the 2nd gen i7 or i5 CPU, this is more than enough umph for whatever you need. As a matter of fact, if you have a GTX 460 + i7 2600k (for example... I have this) you really don't need SLI. OC'd the 2600k and using Afterburner on the GTX provides a lot of power for pretty much anything you can throw at it, including games like Metro 2033 and Fallout 3 at full resolution and max everything; No studdering.
Regarding video conversion, speaking from Nvidia CUDA experience, this is just as fast as Intel Quick Sync and probably faster in SLI. I'll be testing SLI this weekend when I get my new GTX cooler. Right now I'm using only one GTX 460 (and it's fast enough for everything I threw at it).
Right now Virtu is a "trial" software, which means it's probably gonna cost (who knows how much) once it's released "for sale". And while it's only in trial mode, only 3 types of video converters are supported. As with any watered down trial software, you can't add any other programs to test Virtu.
I haven't tested Hydralogix and don't plan too. SLI (or CF) is the better option, IMHO. Here's something interesting I just read on the latest release notes for Hydralogix:
Open and known issues in this driver version
The following are the open issues with current driver release:
Unigine Heaven 2.1 DX11 can take long time to exit
No support for windowed mode
It is recommended to connect the display to the stronger GPU
Running benchmarks while FRAPS application is active may cause crashes (occurs
also when HYDRALOGIX driver is disabled)
3xGPUs mode performs best with 3 identical GPU
Connect the display to the stronger GPU? 3xGPU mode performs best with 3 identical GPU's? Then what the hell is the point? Just use 3-way SLI or Crossfire and be done with it! Adding a 3rd Party software to the mix is going to mess things up, IMO. It even says right there, "Unigine Heaven 2.1 DX11 can take long time to exit". Yeah, I bet it won't take a "long time to exit" if you're just using SLI or CF on your system without the Hydralogix BS.
I had to download one of those supported video converters to "test" Virtu. I converted a 3.5GB DVD to AVCHD format using Intel Quick Sync w/Virtu on the first test, and Nvida CUDA on the second test (Virtu disabled). Here's the results:
Not any difference at all, because the 2nd test that was converted using Nvidia CUDA was about 100MB bigger. And judging by the time it took to convert the files, it looks like it was converting a little over 100MB a minute. I put the Geforce GTX gadget on top of the app so I can see the temp. When using Intel Quick Sync w/Virtu, it stayed idling ~31 degrees Celsius. When I used Nvidia CUDA, it went as high as 61 degrees, but rapidly dropped before I could get a screen shot to show how high it went. You can see my system stats below for what I'm working with. Anyhow, this is probably a little more info than you need, but I'd like to cover all bases in case you had addition questions on how Virtu works or what it's all about.