You should be fine. I flew Atlanta to London with 2 camera bodies, a laptop, 5 or 6 lenses, batteries, chargers, filters and other assorted gear, plus another full bag with all my clothes and personal stuff. Stored both in the overhead compartment - my camera bag was made to fit under a typical plane seat, but wouldn't fit under mine for some reason even though it would've worked under the seat next to mine. Coming back, because I was on a different airline, I ended up just checking my clothes bag and carrying the camera gear on. Basically you never, ever want to check your camera gear.
As far as security goes, no one asked me any questions or even wanted to look in the bag beyond the typical x-ray scanner. I was really surprised. When we were boarding there was a couple TSA people stopping random people to check people with larger bags before boarding and they just waved me on even though I probably had the heaviest/bulkiest bag in the whole line. I'm sure it's all random to some extent but I was prepared to answer at least a few questions about some of the more unusual looking camera stuff I brought.
The bag in question: http://products.lowepro.com/product/Fas ... 087,14.htm