I doubt it. The 1st Generation iPad is slowwwww. Just for perspective; the 1st gen. iPad has a SGX535 which is a 2 gigaflop GPU, the latest iPad air has a G6430 with over 115 gigaflops. The A4 chip is slow, and would be comparable to a $35 android tablet these days.
Sorry, but you can't. The 1st gen iPad is slooooow....too slow for iOS7. There is no way that I know of to install iOS7. Maybe if you jailbreak, but even then, it's going to chug along if you get it to work. The most recent version of iOS that you can run is 5.1.1.