If you'll be doing lighter gaming and internet stuff you won't need a new system for that like vaderpro specced out, but that is an option if you want a whole new main system or something.
For upgrading your current one I would suggest:
Memory-$115
http://www.newegg.com/Product/Produc...82E16820144122
Graphics- $103
http://www.newegg.com/Product/Produc...82E16814102666
or if you want even better:
http://www.newegg.com/Product/Produc...82E16814143046
As for your monitor, I really like Samsung. Good prices, great monitors.Any of these will be fine depending on on what you want more, 17" or 19"
http://www.newegg.com/Product/Produc...82E16824001072 http://www.newegg.com/Product/Produc...82E16824001070 http://www.newegg.com/Product/Produc...82E16824001081
For what you've told us you'll be doing you proc is fine, your mobo may not support a much faster one anyways. Video is going to be a must and after that memory. Prosavage and Unichrome are the worst integrated graphics available right now, those have gotta go.