[quote=Tearstone]Light takes time to travel. The distance from the earth to the moon is roughly a second, but from the sun to the earth takes a little over 8 minutes.. and from earth to mars takes about 40 minutes. [/quote]

That's right, so in a long range battle the best knowledge of an enemy position would be where they were a handful of seconds ago and laser weapons would need to have that taken into account.

[quote=Tearstone]LASER - light amplification by stimulated emission of radiation - Is essentially a columnated spatially and temporally coherent beam of EM radiation, usually in the infrared or ultraviolet range. Of course there are radio wave variations and the like. Granted there's little to disrupt the beam, but the lag time for the beam to travel would make super-long range shooting a virtual impossibility, say something more than 600,000 kilometers for anything smaller than a long range (intra-system ship, say designed to fly to pluto and back), unless flying a stable course in a straight line at a specific rate of travel.[/quote]

Pretty much although a laser would reach a target at the same time as the target would see it firing. Random manouvring would be the best way to dodge lasers so it would really be down to luck. THe maximum range of a laser would be about 1 light second or 300 000km because no matter how focused a laser is, it will still diffuse enough to be ineffective after enough distance. This range still has a full second of time lag.

[quote=Tearstone]Another thought is, there was recently a laser system designed that creates a laser that has the same output as the sun for a brief moment with an interesting form of optical condensing and compression. Would something not be similarly possible with military grade lasers of the day? All that much energy packed into a single shot would be nasty. [/quote]

That laser is located at the National Ignition Facility which is being used in nuclear fusion experiments and is roughly the size of a warehouse. It's also only about 50% efficient if converting energy into a laser beam, meaning 50% of the energy put into the laser is lost to heat and other reasons. It can only really be fired once a day because of the heat buildup. Lasers in that power range are used in this universe to actually launch spacecraft from the surface but would be much too large to fit to a spacecraft. Weaponized lasers would perhaps be in the 75% efficiency range and output of about 100MW.

[quote=Tearstone]Also, what about microwave lasers? [/quote]

They'd work, but the best type of laser to use to damage a target would be UV light. 

[quote=Tearstone]Also, are you taking in communications and sensor lag, as well as power degradation over distance? [/quote]

Using directional transmitters, liekly lasers, degradation likely wouldn't be too much of an issue though time lag would still be present. 

[quote=Tearstone]What kind of accelleration do missiles have available. 20g's? 50 g's? 100 g's? While it might take a laser a second or two to reach lunar distances, a missile pulling 100+ g's of acceleration could reach that distance almost as quickly, and outfitted with a nuke, or even one that splits into multiple warheads could be nasty. [/quote]

Even pulling 100Gs a missile would still take over 10 minutes to travel a single light second. Missiles are useful because they can track a target and time lag doesn't really have an effect on their accuracy. 20Gs might be better. Raching a target at a lower speed makes it easier to adjust its course. I figure that they'd fire their engines once to get up to speed and then only as needed to make course adjustments.

Nuclear explosions in space aren't really that effective. Without atmosphere there's no blast wave and no heat. The only effect would be through radiation which spacecraft spacecraft would be shielded against anyway. A nuke would have to be quite close to have a major effect other than disrupting communications.

Multiple missiles would be quite effective although there would be ample time to shoot them all down so more is better.

[quote=Tearstone]Also, what about particle accelerators, or particle beams. A muon beam might be more effective against a target than a laser, and most particle beams cause a catastrophic failure of most materials they hit, while (as far as I know) inflicting little heat inclination. [/quote]

Particle accelerators suffer the same problems as lasers. 

[quote=Tearstone]Random Question - Have you ever read First Flight or the Sundowner Trilogy by Chris Claremont? (awesome series, some of this I'm actually taking notes from since it's a fairly hard sci-fi setting and similar to this setting.)[/quote]

No. This is actually mostly inspired by the story O Homeworld My Heart written by Angry scotsman 1989 on the alternatehistory.com forums.