Now that you're rooted, installing roms is very simple.

Simply download the zip file and place it in the root of your SD card.
Reboot your phone in recovery mode
wipe & delvin wipe
install zip....

that's it!

Every rom I've downloaded alreeady came with SetCPU app for overclocking.
Do a search for recommended settings.
I have mine at 710/528

Others have it higher.

 

Oh... and might as well recommend what I'm using...

Fresh!!!!!

VERY fast and stable IMO.

http://androidforums.com/all-things...2-1-overclock-apps2sd-update-5-16-2010-a.html

Don't pay attention to the instructions where he says not to wipe. It can be confusing. He's talking to those who already have 2.1 fresh... and updating the new 2.1.1.
For you, make sure you wipe.....

 

Congrats, and enjoy.

1) Download the ROM of your choice to the root folder of your SD card. Don't rename it, don't unzip it. You can either use the phone to download it, or transfer it from your PC. The fastest way would be to download it with a PC, and put it on the SD card using a media reader/writer attached to the PC. That way you don't even need to boot into or configure the EMA-installed ROM that you are going to throw away.

2) Power up the phone into Amon_RA's recovery boot by holding the Vol-up + End/Power buttons at the same time (until you see the screen light up).

3) Scroll down to the "Wipe" sub-menu with the trackball and select it by pressing the trackball. You'll get a new menu here; repeat the select and click action for both Wipe Data/Factory Reset and Wipe Dalvik cache. For each of these options it will ask you to confirm with yet another trackball click (or use a volume button to cancel) After you have performed both wipes, click on one of the volume buttons (read the screen for directions) to return to the top-level menu.

4) Use the trackball to scroll down to the "Install ??? from the SD card" option (sorry, again I can't remember the exact text); click the trackball once, and it will display the names of all the zip files in the root of your SD card; scroll once more (w/ trackball) to the correct .zip file (probably there will be only one, but who knows), and click with the trackball to select it. Click one more time with the trackball or use the volume keys to cancel.

5) Reboot and configure your new ROM.

First, pick a ROM with OC' enabled and working correctly. It will have the OC control app (SetCPU) pre-installed. You'll need to do a little reading and playing around with that app - it has some subtle behaviors. I strongly suggest you read zanfur's ENTIRE post on XDA. It's a long post, but it explains exactly what is going on and what the risks are.

eu1

 

+1 I'm loving the Fresh 2.1.1

 

I liked fresh 2.1 for a while but had to switch back. It definitely was very fast but I couldnt get used to the black and white icons. Comparing the ones between that and aloysius I liked aloysius better. I had a hard time opening up my app drawer and being able to find my app right away because they all looked the same being grayscale LOL. Plus the soft keys didnt light up and I had to use quick boot again.