Shit...get at least 4 gb of ram and nothing older than a Core 2 duo processor. Anybody will tell you it all depends how much your willing to spend but if you're going to compromise I wouldn't suggest going beyond that.
Also, if you know how to connect it then you should be able to plug your old hdd into the new tower as long as you got enough power ports and a sata cable for it (also a additional females in the chipset which newer pc's usually have). The only issue I would imagine you might have is if, like Blue pointed out , the hard drive itself is part of the problem. If it isn't then you'll be able to boot from your old hdd and just take advantage of the extra memory from the new hd. I would suggest learning how to partition however, to better protect your data in the future.
On a side note. Coke and Jack are my new best friends.
Also, if you know how to connect it then you should be able to plug your old hdd into the new tower as long as you got enough power ports and a sata cable for it (also a additional females in the chipset which newer pc's usually have). The only issue I would imagine you might have is if, like Blue pointed out , the hard drive itself is part of the problem. If it isn't then you'll be able to boot from your old hdd and just take advantage of the extra memory from the new hd. I would suggest learning how to partition however, to better protect your data in the future.
On a side note. Coke and Jack are my new best friends.

