Let's see if we can consolidate the issue, because you've got two threads going, which are more or less about the same thing: getting you back playing your game(s)?
In this thread, you're having over-heating issues with your on-board graphics: Installing a custom fan.
. Simple enough. You've got to either get a card because the game you're playing is too demanding, or dramatically increase your airflow... or just clean out dust bunnies?
If you want to spend no money, which is probably a good idea given the age and technical specs of your current rig, I'd just take the side panel off and place a room fan facing inwards. It's ugly, but it'll get the job done, and it won't cost you a dime.
If you're insistent about getting a card for your current rig, which is, by all accounts, ill-advised, then by all means, go for it... but it would probably be money better spent on a new machine? Afterall, you've lasted this long with that machine, right?
To answer your questions: low profile just means "thin". Many of today's gaming cards take up two slots; low profile cards just use the one.
I have no idea what's wrong with your browser? Have you tried clearing your cache and coming back? That usually does the trick.
1GB of video RAM means that you'll be able to use high amounts of anti aliasing and anisotropic filtering when you run your games. However, in your case, since the gpu you're looking at isn't that powerful, and the cpu you have pushing the gpu is also relatively slow, you won't be able to use high amounts of AA or AF... so for you, having 1GB of onboard RAM is meaningless: you can't use it. Well, I mean you can try, but as soon as you see it chugging along you'll turn off all the AA.