OK, i want to put together a small battery back up / solar system.  I know very little, but i want to start with the batteries and inverter first for a battery back up and add the solar later.

How many of this battery would it take to equal a car size battery?

I am thinking of going this route since they are sealed and would not put off hydrogen or require filling.

Is this a good type and size of battery?  would i be better off going with something bigger instead?

Get bigger and a deep cycle battery.   Paging CJnh

thats only a 7ah battery. car batteries have a lot more ass.

first off you have to know your LOAD required as well as how long you will need to sustain it between charging.
then you can figure the size of the charger required.

a 7ah battery, forget it. as well as multiples of them.

it would cost you over $300 just to match one $50 car battery. you would be better off with 2 6V golf cart batteries. off gassing isnt that big of a deal as long as the batteries are in a vented area. 2 6v batteries can be had from sams club for(i believe several people have said) $60 or so.

This.

Do not use a car battery or anything similar. It is not made for that. Use the right components the first time or keep throwing money away when the batteries don't last. 2 6v golf cart batteries are perfect for a small setup to learn with.

You also need a charger unless by inverter you mean one with a built in charger. But they are not cheap.

you have to know the load, then pick and choose........

Not a bad idea to have some of the small batteries handy. Buy a half dozen and make yourself two small battery banks. Great for LED lighting. Easy to charge via solar. Easy to carry, etc. I purchased a dozen of these (CSB brand) and picked up the action sport boxes from Northern tool. Very useful for the small load. As TrKarl mentioned, don’t even bother with car batteries.