1000 pt IG army without tanks:
HQ-Weaponry is okay. Drop the Chimera (by itself, it will draw fire and get knocked out early on, unless you just want it for fluff-Colonel's don't march). Drop the Frag Grenades (they let you go in order of initiative on the rare occasion when you charge an enemy in cover-You will rarely get to use them, and when you do, unless you are facing orks, tau, Salamanders or other IG, you will still go last). 98 pts saved
Command Teams-Drop the Vet Sgt (the LT already has Ld8) and the frag grenades. Vet Sgts are occasionally handy for an extra plasmapistol, but a plasmagun is cheaper and has better range. The leadership only comes into play if the squad is out of range of your officers. Save 15 X 2= 30 pts
Tactical Squads-Drop the Vet Sgts, same reason as above. 6X10=60 pts
Save the 188 pts shown above. With these, you could buy an anti tank squad with 3 lascannons and arm your tactical teams better. You could pick up two heavy bolter squads and arm your tactical teams better. Or you could add two more well armed tactical squads. You could swap out the autocannons for missile launchers -or a mix of heavy bolters and missile launchers.
Basically, you need to trim the fat (Vet Sgts, and frag grenades) since they suck up points but provide little real benefit.
Then you need to add some anti-tank punch. You need to at least be able to glance 14 armor. Being able to penetrate it with a few weapons, in different squads, is even better.
Personally, I would give each tactical squad a missile launcher, and each platoon command team a lascannon if I were going with an "all infantry" force. That way, everything is a threat to armor, even if its main job is to kill infantry.
Best of luck.