I'm trying to figure out what CPU to get with a budget of $200 or less
It looks like the pentium IV 3.0 but there are many to choose from, which core? which is the faster.
And how about AMD from 2600 to 3000 they all seem to be 2 ghz, boy that's confusing.
then the MB whew!
Well first of all we need to know what do you plan on using the cpu for, To play games, video processing, internet use, .... Are you upgrading a motherboard that you already have, and so on, and so forth. Drop what the specs of your computer are what you plan on using it for and that would help alot more.
Yes you would gain some performance going up to a 3000+ chip, but this wouldn't be a big enough performance gain to justify the cost. I would stick it out with your current machine for right now. It should be more than plenty.
Another 512 MB would help some. If you do buy new memory I wouldn't buy 2700 again, I would buy something faster, that way when you do upgrade in the future, your RAM will be ready, and you will just have to replace the single stick of 2700, instead of two sticks of 2700. The different speed memories should work fine (The faster stick will run at 2700 speeds), assuming you aren't overclocking (Using different speed RAM chips can cause weird stability problems in some cases when overclocking.).