[The Fifth Horseman]

That's what you have Targeters for. You take one Targeter coupled with Bolter, you have them on all Bolters.

Imperial Fists should take heavy weapons on all their troops - Suspensors allow their HW troopers to move as fast as the Bolter troops do, while Combi-Weapon and Bionic Eye make your commander an unstoppable plasma-gunner (of course, whatever your strategy guide tells you, Imerial Fist commander should be packing a Heavy Bolter). Don't forget to take Targeters on the Plasma Gun and Missile Launcher, either.

Blood Angels in turn should concentrate on close combat.
Close Assault Blades allow you to attack the enemy diagonally. IIRC, most of them won't even really be able to retaliate. Couple with Bolt Pistols and Bionic Arm for the Commander. Maybe also a Melta Bomb or Force Field. With the first, your Commander will simply FRY any Dreadnought stupid enough to come close (useful in Search & Destroy mission).

Oh, and anyone knows about that supposed expansion for the game? Was it ever published for PC version?