Will upgrading my CPU and GPU lower my ping?

No. Your internet has nothing to do with your GPU and very little to do with your CPU.

But isn't the ping also about the lag?

Yes, bad ping makes you lag.
but its your internet that causes it.

Not always. I've got a pretty badass internet connection, and I would lag as shit on - let's say - Battlefield 3 Multiplayer just because my PC wouldn't handle rendering the game itself. :P

LOL.
My friends have a 512KBPS internet and they are playing Realm of the mad gods smoothly.
They have a pentium DUAL.

I have a 1MBPS internet and I play realm of the mad gods and it's damn laggy.
I haz Pentium 4, gonna upgrade to core 2 duo in a week.

Well ping mostly comes because youre pc wants to crash or youre pc is too full and too slow
Like if you hav emuch programs and stuff it will lagg youre toribash
What can result into ping
I would recomend before you change anything
To dont play tori on big screen
to close everything like messenger and internet and stuff if youre playing tori
And try cleaning it up at youre desktop deleting things you dont need etc.
It will help alot like it did to me

Ping is a measure of internet capacity.

Lag is not JUST ping.

Ping can ONLY be caused by internet connections in any meaningful manner.

Every other type of lag, such as rendering lag or computational slowness, is due to your computer not being able to process information fast enough, or load information fast enough.

Bad PING would imply that your computer cannot RECEIVE information fast enough.

Please don't confuse them. It drives OCD tech-people insane.