i'm gonna assume you need to buy a new set from a store cause it's for your company (the 2nd market offers more options, but may have issues with receipt/warranty, and might be a hassle). A friend of mine just bought a Nikon D3100 with a kit lens for $500+ (a big chain store, may have been Harvey Norman, i can't rmbr). if that offer, or something similar, is available, i'd go with that, plus a SB-700 (SB-600 no longer available, right?). Got spare cash? Buy spare battery and a set or 2 of Eneloops.
An entry level body and kit lens can do more than most people think, and in capable hands, can be used to cover most events. Learn to diffuse the flash -- Stofen or just bounce flash with a small reflector (i've used a business card and rubber band for flashes without a built-in reflector). Use the centre focus spot -- learn to focus and recompose quickly. For the Nikon, TTL BL, and Auto iSO is pretty good, up to 1600/3200. With a regular 18-55 kit lens, I'd stay ard f/5.6 - 8 (I'm normally on Aperture priority, but Program works too. Need to get a tighter shot? Get closer. Let the action flow naturally, but don't be afraid to direct a little. All that was for indoor events. For outdoors, i love fill flash, but if you aren't sure, ditch the flash and use natural light.