Many of the LED lightbars run AC current just fine, in fact, there is a company selling LED lightbars specifically designed to run on low wattage AC current from a quad, complete with handlebar mounts and everything (check out http://www.bajadesigns.com to find ATV specific LED lightbars).
I say many and not all because those LED's are expensive....and I'd hate to say that all of them work with AC power and then hear about someone frying their $600 lightbar because of that generalization.

Here's what I posted about it on the old website in reference to LED advantages:
*links don't work anymore, sorry.  Might try lazerstar's main website and navigate on your own though*
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-they don't need to be warmed up, instant on (HID's spike during warmup, LED's don't)
-they don't need any cool down time to restart (some HID don't need cool down time, but some do or they won't restart at all)
-they don't need a battery
-they require less electricity to run (keep in mind you have to charge the battery AND run the lights on any HID setup)
-they're as easy to install as a standard halogen light
-they have a better pattern
-no charging system or rectifier is needed, use existing wiring

A single LED housing can be set up to provide multiple patterns (flood/driving/spot all in one).
Or, mount a flood light on the frame and a spot/driving light on the handlebars.

http://www.lazerstar.net/blog/?p=243/
http://www.lazerstar.net/application...-led-light-bar

A stock stator won't be enough to power HID lights, you'll have to go with bigger lighting coils (I think Ricky Stator is your only option at 130W, $40)
100W of LED light is going to be like two 55W HID's, and I don't think it's possible for a 130W charging system to run two 55W HID's.
That would equate to ten 10W LED's, or 33 3W LED's.

For 3W LED's, you can use these two together:
http://www.lazerstar.net/brands/lx-l...1054_1059_1089
http://www.lazerstar.net/brands/lx-l...1054_1059_1089
Or, you might actually get by with 40 LED's (120W), but that'll bring it real close to the 130W limit:
http://www.lazerstar.net/brands/lx-l...1054_1059_1089

For 10W LED's:
100W total: http://www.lazerstar.net/brands/lx-l...1054_1059_1088
120W total: http://www.lazerstar.net/brands/lx-l...1054_1059_1088

Or, use 2-3 of these:
http://www.lazerstar.net/brands/lx-l...1054_1059_1088


Only downside is that they're currently ridiculously expensive, give it a few years and they'll be just as cheap as HID's.
You might find them cheaper elsewhere on the net though...
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Now, if you don't want to bother with AC powered LED's (or you don't have lighting coils etc.) then you still have another option...use a big lipo battery.
A 5,000mah 3S battery will run a 200W lightbar for 15-20min (that's a LOT of light, and not a big battery).
-3 of those batteries will give you about an hour of runtime
-100W lightbar will last 30 min on a single battery
...you can probably do the math past that point.

Grab a few batteries here:
http://www.hobbyking.com/hobbyking/store/__86__85__LiPo_LiFe_NiMH_Battery-Li_Poly_All_brands_.html

Here's a cheap 5,000mah battery ($25)
http://www.hobbyking.com/hobbyking/store/__6501__ZIPPY_Flightmax_5000mAh_3S1P_15C.html

B-grade lipo (cheaper, but won't last as long)
http://www.hobbyking.com/hobbyking/store/__18507__B_Grade_5800mAh_3S_25C_Lipoly_Battery.html