I am in the market for a tripod. I wanted to know how important it is to follow the maximum load rating for the legs are. I am looking to purchase a set of legs that's maximum weight load is roughly 5-7 lbs shy of the weight I plan on putting on it. Money is an issue and do you think that these legs combined with maybe sandbags to hold it down will be sufficient for the weight I plan on putting on them?

legs I am looking at: Bogen / Manfrotto 351MVB2K
legs that I would like if I had more money: Bogen / Manfrotto 525MVB

I think you will regret spending money on something that doesn't do what you need. Wait and get the right equipment for your rig. [EDIT] Or rent for the time being.

Sounds like you want to put about 25 lbs on the 351MVB2K? I'd also recommend against it. Although the legs probably have a safety factor beyond the weight rating, by exceeding it you're risking breaking the legs (somewhat likely) and/or having the leg locks slip (more likely). With that much weight on it, if one of the leg locks give way quickly, the entire tripod will probably fall over very fast and your camera will likely suffer heavy damage.

25 lbs is a lot of mass and inertia. I'd recommend a tripod that is rated for double if not more of that weight.

For a 25lb camera you'd really need 100mm (or 150mm) bowl head intended for the larger cameras. Sachtler Video 15 at least, if not a Video 18 or the Vinten, Cartoni, O'Connor equivalents. Lightweight tripods and the heavier cameras don't mix that well.

If it's just a short shoot, it's best to rent one.

I'd recommend the Miller Solo 100mm legs. It's a great tripod to own because they are compact, lightweight, and have a great height range (ditch the hi-hat and the 8-step ladder). 65 lb payload and are practically nuke-proof. Add any head you want.

I recently bought these sticks after using a heavy OConnor tripod and could not be happier. They will last me for years of heavy use in most conditions, and if I need something heavier for a jib or whatnot, renting a tripod is cheap!

My 2¢...

(But as Brian said, if it's for a short, renting is not a bad idea....)