What model eMachines do you have? Why would you want to upgrade the powersupply? Are you having problems?

Ok i have the T2245 and my pc restarts on games and my games freeze but I wanted a bigger power supply because Im getting a 3.6GHz P4 HT in a few weeks

and you are going to run that in a micro case !!

y not?
i already have 3 fans in my case

3.6ghz? Not possible..

Also, just to note, if your current PC does not support HT, then odds are your motherboard doesn't. If it doesn't support HT, then it probably doesn't have an 800mhz FSB.

So you will be running at a 533mhz FSB with No HT.

I already upgraded my mobo to a Asus one that supports 533MHz FSB and HT and goes to 2.8+ GHZ

Now I already ordered a new case with a 350watt PS

What I was wondering if the reason because my pc is restarting and running video games so slow and freezing be that I was running a strong video card but I was only running a Celeron processor?
And should a Pentium 4 and a bigger PS fix this?

i tested my memory and its not defected or anything
I reinstalled my OS 2 times and Im still getting the same thing
I ran 2 scan disks and my mobo and video card is brand new, BTW this used to happen with my old mobo (and its onboard graphics so it isnt my new video card) but it only happened once or twice.
So Im guessing it has to be either my CPU or PS

For information about 'freezing':

http://www.daniweb.com/techtalkforums/thread2375.html

Ok, its fairly obvious your doing this upgrade for gaming reasons. It also sounds like you want to go cheap on some hardware, while all out on other hardware, and I understand the motivation, I was there a few weeks ago (as I just got a P2 2.4ghz/800Mhz FSB mobo) and just decided to spend the money on a good case.

A good power supply is critical to your system, especially if your going to be using a P4 of that caliber. If you have a really nice motherboard, then you can get away with a lower power supply. If you bought a cheap motherboard, not possible.

Assuming you want your system to last without 'freezing' from your power supply or lack of cooling, purchase an ATX (not micro) case with an ATX (not micro) power supply. I am going to purchase an ANTEC power supply/case for about $80. I looked at a noname brand for $30 and though. Hmmm.... ok, I could get a noname brand with no cooling, stuff all that hardware into a little box, and have a horrible time cooling the system and keeping the power running properly. I then came to this conclusion after floating around FRY's for a half hour:

If you want a small system for games, buy an Xbox. If you want a PC for games, purchase the appropriate hardware for the job, because you get what you pay for.