Upgrading the CPU?

I have a really old emachines desktop and this is the current CPU:
Intel® Celeron® Processor 1.80GHz (w/128KB L2 cache & 400MHz FSB)

Its extremely slow and I was reading around and I read that I might need to upgrade the motherboard as well. Well I went to their live chat support and the guy told me that as long as its a mPGA478 socket type it will run on the motherboard.

My question is, is that the same as a 478 socket because I found some cheap used ones on Ebay for around 20 bucks.

Would this one with 2.8Ghz and 1M cache be better than:
http://cgi.ebay.com/Intel-Pentium-P...ryZ14293QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Or this with 3.0Ghz and 512 cache:
http://cgi.ebay.com/Intel-Pentium-4...ryZ80143QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Now if those aren't the right ones to fit does anyone know where I could find one that has a mPGA478 socket. I read that its the same as a socket 478 but I just wanna make sure.

And will the installation be hard?

 

1.yes, mPGA478 is the same as socket 478

2.I'd go with the 3GHz Pentium 4.

3.No replacing CPU's is quite easy. Just pull off the heat sink and fan, pull out the CPU (your old one), put in the new CPU into the socket, then install the heatsink and fan.

 

with some cooling paste but yea, he pretty much said it all.