Any welders in here?

Hey, I am planning on starting to weld, what is a good machine for welding like exhausts and manifolds and roll cages and stuff, i know there is mig and tig welding, but whats the difference and which one is the one that i was for what i'll be doing? thanks for the help, this is confusing.

oh and whats the best spray for breaking apart rusted together things, such as my exhaust manifold to the exhaust pipe bolts?

I'm not a welder but I know that tig welding is for precise welding and mig welding is not as precise. Do a search.

I hear PB Blaster works for stubborn bolts.

Go to the fabrication forum for all the info you could ever want on welding (go to AF main menu, cars in general, its at the very bottom).

PB Blaster is about the best stuff for loosening rusted bolts.

i weld alittle and if you are going to buy one i would look at the lincon 125 at sears it about the most reliable and the most bang for your buck about $399

Here's the best advice I can offer you....If you're new to welding and even if you're pretty sure you know what you're doing, it's always a good idea to check at your local college or even highschool to see if there are some welding night courses. They're usually quite inexpensive, but the best thing is, that you can use and learn on their machines so you're not putting wear and tear on your own stuff that you paid for. Even if you do have experience it never hurts to get a refresher and some new tips. You'll probably be exposed to a number of different processes so you'll know what you like to do, and how easy/difficult you find it so you know if it's worth spending the cash on a machine of your own...what good is a $500 welding if it's in the basement collecting dust right?
Also you get to use thier materials, it would really suck if you bent up some nice tubing for a cage and then blew holes all in it trying to learn how to weld. Sometimes you can find scrap but it's a whole lot better when they give it to you to learn on.
The last advice I can give you is that MIG or GMAW as it's now called is probably your best bet, but make sure of a few things....One, make sure the machine you get is Gas/Gasless built in....conversion kits can be expensive and it's great to have the option of using gas or not. Also for what you're doing you probably won't need more than a regular outlet, so don't get anything too big that runs off 220V. The naming of the machines is pretty standard that a 150 is about the biggest you can go at house current before you need a special plug....the higher the number (90, 110, 135, 150) is basically an idication of how thick you can go.
Ask around, but www.millerwelds.com and www.lincolnelectric.com would be too great starting points. Campbell Hausfeld also offers a nice entry level machine similar to the other brands but costs quite a bit less....or look in the pennysaver for a good used machine too...
Good Luck