Our Comic book store is having its release party tonight and is hosting a 3 round 500 point Flash tourney.

This is my first attempt, so any help is appreciated.

Captain (96 Points)
- Storm Bolter
- Chainsword
- Iron Halo

Tac Squad 1 (161 Points)
Srgt - (Bolt Pistol and Chainsword)
7 Marines - (Boltgun)
1 Marine - (Heavy Bolter)
1 Marine - (Flamer)

Tac Squad 2 (170 Points)
Srgt - (Bolt Pistol and Chainsword)
7 Marines - (Boltgun)
1 Marine - (Missle Launcher)
1 Marine - (Melta gun)

Scout Squad (70 Points)
Srgt - (Bolt Pistol and Chainsword)
2 Scout - (Boltgun)
1 Scout - (Heavy Bolter)
1 Scout - (Shotgun)

Like I said This is my first time so please help!!!!

Current captain with stormbolter+ chainsword+ iron halo=91 points IMO
I'd find a way of giving him a power weapon (drop storm bolter- he is your big close combat thing,keep the CCW, a bolt pistol is best)
If its 5th ed maybe find a way to give him termie armour so he can absorb squad wounds.. for the same points as that iron halo he gets the 2+ agaisnt gribly fire, an acceptable invulnerable..he loses the chance of a bolt pistol..but he gains an attack from the termie armour (you gotta love the smurf codex:))
unfortunately even if my maths are right..you'd still need another xx points free to get the power weapon(thats a big loss somewhere)

Tac squad one, not overly powerfull, but a good multi tasker

Tac squad two I think in that small point bracket with other guys having rapid fire weapons I'd opt for a plasma gun over melta if you got it. (less chance of super tanks in 500 points(any other rules like no AV14 or anything your not saying?), you won't be able to assualt after firing bolters so you'll aim to maximise fire and weather assualt generally)

Scout squad (yay!)
Why the shotgun? I'd be tempted to call it a bolter..depending on how you want to play the scouts I'd even suggest giving your srgt a bolter too (free as well) but thats because I use my squads as cheap fire support, if you want them to be combat support, then I'd reckomend more men and CCW and bolt pistol (but they never really did it for me)..
v late edit: oh hang on..are you trying to do the clever wound wrapping thing? bravo Ignore me

LATER edit- or you could split your 2 big squads into 4 smaller squads, disadvantages= makes your special weapons slightly more prone to going down. advantages- gives you more ability to split fire (eg. agaisnt tau and eldar etc with swarms of small squads around the place) so you don't wast e shots (e.g. a missile launcher against a tank then a split squad frees up the other 5 guys to shoot infantry etc) and he has to split his fire shooting you (because he'll have to kill everyone off) making your opponents life a bit trickier