I'm iffy on the captain here, in my 500 pointer I've got a barebones libby running around because they can get away with it, captains need those upgrades to be real headknockers (but they are higher caliber headknockers). Looks like this.
Libby -100 Avenger, gate
Tac 1 (10) -170, flamer, missile
Rhino -35
Tac 2 (5) -15, powerweapon
Razorback -40
Land Speeder -50
Captains can swap their bolter/bolt pistol/ccw (start with any combination of the three) for the upgrades. Basically, they get up to two upgrades, and you choose what is swapped. Powerweapon/Bolt pistol is common, though some prefer Combi-weapon/Lightning claw or Relic blade. Barebones preds are alright, though at 500 I try to find the extra points for a whirly (or a typhoon, for a little extra). If you can get ten more points somewhere, I'd take a second speeder like the one you have. Not sure what I'd do against Chaos since you're going all mechanized, but a tac squad full of plasma makes a good firebase at these points. It's rare you'll need something like melta to pop something, and the plasma doubles for light vehicles and heavy infantry.