Do they both have SSD's?
The Air's saving grace would be the SSD, but if you are hoping to do some professional work with these programs then I wouldn't suggest either one of them.
As already said, neitehr of them is gonna have any significant advantage over the otehr. Where the otehr has a stronger processor, it only has a built-in graphics controller when the otehr has a weaker processor and a better graphics system. On balance, they will be pretty much the same in terms of working experience...
This is the After Effects-specific reply only: neither. They're both low-horsepower machines.
Why? They only have 4 gigs of memory. What does AE need to use multiprocessing? Lots of memory. On either machine you'd be limited to using just a single core.
Not the most effective use of your processing power, is it?
Now, What computer would be faster for basically everything In After Effects, Premiere Pro, Flah, and all those programs, WHATS FASTER???
As said by others, neither. Even a severely handicapped elderly snail is way faster. Both systems are below minimum requirements, but maybe you can edit some very short (less than 10 minutes) SD DV material clips without effects if you are the patient type. Nothing more.
Okay Thanks everyone. okay, so I obviously not going to make any big big big movies, just a few shorter ones...at max 10-15 mins. If I upgraded my Windows to 8GB of ram, would that make a big difference?
That would be one step, but you need about four steps to make either system barely acceptable:
1. Better CPU and mobo.
2. Better memory.
3. Better video card.
4. At least 3 7200 RPM SATA disks.
Effectively you need a new system, but you can continue using the Macbook Air and the AMD for your kids for some games.
As Harm stated, you'd still need a major hardware upgrade just to even run Premiere Pro to most people's satisfaction. No system with a dual-core CPU - not even a desktop - performs as fast as even a mediocre-performing quad-core CPU-based system. (For example, I got a dual-core i3-2100 system to achieve around 500 seconds total in the PPBM5 benchmark - but it took a GPU that costs significantly more money than the CPU, RAM and motherboard combined to achieve that result.) And since both of your laptops have only dual-core, low-clocked CPUs and lack any NVIDIA CUDA GPUs whatsoever, expect either system to perform at least 40 times slower than a fast i7 desktop Windows 7 PC.
So, in your case, given your current equipment, it would be more like "slower" and "slowest". In fact, the AMD Turion II can barely even run Premiere Pro at all since it performs slower than most of the Intel Core 2 Duo systems (both laptop and desktop).