Well, here's your army first, with 1000 points:
Ok, I played marines for two years, and learnt quite a bit about the difference between the portrayal of units, and their real abilities, and I went through a helluva lot of army lists doing it! Now, it all depends on personal taste, and of course what type of terrain and what opponents you play, but for me, there would be a few dire changes needed to that list.
1. Bikes. Just don't go there. EVER! Quite possibly the worst Space Marine unit, they are little more than normal marines with some more movement. They get owned in CC, owned at long range, owned at short range. Just forget they even exist.
2. Command squads. I've always been against them, however I did take one to Conflict Manchester, having beefed it up to ridiculously beasty proportions (about 310 pts!). Needless to say, I got owned in two of my three games. They are on foot, so move too slowly for an assault unit, and to make them any kind of reasonable force in CC, you have to spend a lot of points on them, far too many in fact. You are always much better off with an assault squad led by a power fist wielding vet sarge, and a jump pack equipped chaplain. IF you had a rhino transport for them, then maybe. But you don't, so they will just get shot up at long range while slowly foot slogging it across the table.
3. Commander. As I said, you're better off with a chaplain, but if you really want a Captain, don't give him a storm bolter, he loses his extra attack, which is a very bad thing! You should really be looking at Termi honours, power weapon, plasma pistol, for 6 attacks on the charge. I did have a captain like this, but updated to the flying chaplain as a foot slogging HQ unit doesn't have enough tactical flexibility. Artificer armour isn't worth the points, neither are thunder hammers. Master crafted, however, is usually a good investment if you have some spare points.
4. Dreadnoughts are good. Very good. Go for the lascannons and close combat arm for a heavy weapon shot that doesn't take up an entire units firing (good for picking off or finishing off tanks and transports). This way, you don't lose the CC strength when its crunch time.
5. Tac squads. Those two squads you have there are entirely pointless. Best thing you can do is to take two squads of 6, though 5 if you're strapped for points (6 is better for morale but I usually use 5). Give them missile launchers, and sit them in cover close to your edge of the board. Shoot stuff. If you're facing swarm armies, use frag, if its tanks or marines, use kraks. Nice and versitile. careful of that fallback distance though, you don't want them running off the end of the board!
That army list as it is will get completely owned if you're playing anything like a decent opponent. When making army list, you HAVE to consider the tactical application of each unit. Those tac squads are useless, the bikes are useless, the Comm squad is beasty but slow, the Dread is good...
Personally, I'd be going for something more like this (naturally this involves more investment, but I don't know what you already have soo...):
HQ:
Chaplain Reclusiarch with Jump Pack, plasma pistol, terminator honours, frag grenades, master crafted weapon: 151 pts
Troops:
2x Tactical squad with 5 marines, with missile launcher and plasma gun: 190 pts
Fast Attack:
Assault squad of 8 marines (inc sarge), with Vet sarge (see below), 2 plasma pistols, furious charge (due to chapter trait), frag grenades: 185 pts
Vet Sarge: Power fist, terminator honours, plasma pistol, frag grenades: 77 pts
Elites:
Dreadnought with twin linked lascannon, spotlight: 126 pts
Heavy Support:
Predator Annihalator with Lascannons, spotlight: 126 pts
Vindicator : 125 pts
Total 1000pts
Sit the Tac squads at the back in cover, shoot stuff, then when they get closer, use the plasma guns. Hide the Dread and Vindicator nehind cover in set up, then pop the dread out and shoot, and move the Vindicator forward until it can shoot a nice big batch of infantry. Sit the Predator at the back, in a position where it can shoot lots of armoured targets like tanks, but try to minimize the return frie from heavy weapons. Meanwhile, the chaplain and assault squad should move forward, sticking behind cover, until you can jump out and assault. Thats 4 plasma pistols in that squad, a possible total of 8 plasma shots. Scary. Plus, thats 6 power weapon attacks from the Chaplain on the charge, 4 power fist attacks from the vet sarge, and loadsa other attacks from the 7 normal guys. They all have furious charge from the trait, meaning they get initiative and strength plus 1. This is a VERY beardy squad, and is a whole lot more flexible than your command squad.
This is my army list, and it took a lot to beat it. Its weakness are usually enemies like Tyranids who are somehow able to defeat the assault squad, and kill enough of my firepower that their assault troops get across the board to my back line (However, I did manage to assault a carnifex with my Assault squad, and kill it in one go, with no return losses

)
Obviously, this list might be a bit much for you to get all in one go, but having tried most of the list options available to me, this is definitely the best marines army list I have come across, having tried infiltrating my entire army, putting them in rhino's, giving them allies, having no vehicles, having all shooters, having lotsa assaulters...everything, this has been the best for me.

Hope it helps.