-what squad will the two hq's follow, drop the comib-weapon and krak grenades from the marshall.
-the vow that allows you a invul save and resistance to pinning might be more useful with this force as you have no transports and it is a lot cheaper
-try to upgrade the other speeder to a tornado
-adding another pred would help
-duplicating squads will also go a long way, make the two close combat squads identical and if possible the two long range as well, the mulit-meltas might be better instead of ml and with plasma will give a pretty good AT unit
something like this might do well
x2-6 initates w/ flamer and pf 6 neophytes-177(354)
x2-6 initiates w/plasma gun, multi-melta-112(224)
Marshall w/power weapon, combat shield, bolt pistol(101)
Emperors Champion w/vow with save i think (105) total
2 Land Speeder Tornadoes(160)
2 Predators w/ tl-las and hb sponsons(260)
Assault Squad w/power fist(191)
Dread w/ ac(105)
dropping the dread and adding might be better but keep the dread cheap if you use him, chances are he wont last long