I built my PC this past summer, it's got the Intel i7-2600k, 4GB Corsair XMS3, and two Nvidia GTX 550 Ti in SLI. I have an open PCIe slot so I'm thinking the Blackmagic Intensity Pro would be fine. I don't need mobile solutions since I'm doing this at home on my PC, but mostly because my laptop is garbage compared to my PC.
and the only thing I'm looking to work on for the time being is iM@S.
As far as software is concerned, I have the Adobe CS5 Master Collection, so I do have Premiere Pro for encoding. In addition to this, you're saying I should try virtuadub right?
Well, that's new (and sort of what I'd recommend actually) although due to SLI, you'll need to check the PCI-e lane total and how many lanes that second card is running in.
This is where I get very slightly technical (and goes to show how much research I put into stuff like this) and I can't make it any simpler.
There are a total of 16 available PCI-e lanes (the board can physically hold more, but this is how many will be running at the same time) on the Sandy Bridge i7 platform. This is for all devices barring the first video card, which gets an additional +8 lanes.
(This is down on the 32 lanes +8 that the i7 9xx series runs on, and the 32+16 that the AMD chipset runs on)
Normally this isn't a problem, unless your motherboard does the following:
8x+8x for Video card 1 + 8x for Video card 2 + 0x + 0x + 0x (If there's a 5th slot.)
This is a straight out 'Check your motherboard manual' thing. If it DOES do that, you'll have to find out if it's automatic (namely a slot detection) and if so, how to tell it to NOT do that and tell it to distribute the lanes so the BMI is always with the 1x it needs.
Mechanically supporting PCI-e and pulling the data out of it are two very seperate things. Boards will crash if you try using more throughput than can be supported.
If you're running a sound card out of an additional PCI-e slot, your allocation may look more like this:
8x + 8x + 4x + 1x (assuming 4 slots total) or 8x + 8x + 4x +1x +1x
That's doable (if you have the space.) although it leaves your expansion options a little limited.
I have no idea what your board configuration is, but PCI-e management matters. It's more for future notes, particularly if you intend to run a RAID/SAS dedicated card (The moment it loses the full PCI-e lane access, the board WILL crash causing a Kernel Panic and/or blue screen) and the cards will often WARN you in the manual over such an event and to plan accordingly.
It might also be worth noting if you experience crashes during the record process - your solution MAY be to pull out the SLI support card.
Even with all of that, I still would advise PCI-e over USB3.0 though. USB 3.0 is flakey from reports, even though the Shuttle supports 480p. (The card doesn't)
That's mostly for later - you should have native RAID support on the board, and you can use that (or a single SAS on SATAIII) to start with.
As for the software side, I suggested Virtualdub only because I don't really like Adobe Premere Pro for basic operations - If trimming frames and slapping a watermark is what you need to do, you probably can do it far faster on Virtualdub than on Premere Pro, really.
I didn't pay for the copy I got (It's a site licence copy that was gifted to me by a business when I first started and still do a bit of freelance for.) and to be honest, I don't like it very much, since it is usually overkill (and clunky too which is a bad combination when you're in a hurry.).
With encoding, I don't use (and never have) used anything from Adobe for encoding - I cut my teeth using x264 via command line, then moved to Carbon Coder after another freelance job scored me a licence (as payment) and although overkill, is by far the most brain dead easy solution for h.264 encodes while being scarily effective. If it wasn't a couple of thousand, I'd strongly recommend it to well, anyone. It's designed for broadcast studios for mass, rapid and automated distribution.
I still use x264 by command line occassionally, mostly for Touhou type work.
Watch folders (ie if something shows up in it, it'll automatically encode then execute any instructions you put on it), all sorts of encoding options and automatic uploading (It does ftp only though) with all sorts of suboptions is pretty useful, although for most part, the real fun is in the administration side which manages the automation. If you can get your hands on it... *cough*
There would be only ONE thing I want to find (and I sincerely doubt that anyone made such a program) and that is to have a program that can be placed on watch, and upload a video to youtube while reading a txt file (in XML I guess) to automatically populate the description and what have you.
But that's me being lazy, and getting way ahead of your requirements at this point.
You'll want to check the PCI-e lane situation (just in case) then pick up the card and maybe a SSD/enough HDs to get the speed you want. Just note what I said about space and cost and stuff.
But you should do relatively well for encoding. You might also want to look into broadcasting games live, and for that I'd suggest Wirecast. (Maybe Xsplit has learnt to behave, but last time I tried it, it liked hijacking the BMI drivers, which is a bad bad idea...)