Before flashing CM7 on your Galaxy Ace.

Look at screen shots of CM7 here

What features will I get?

A2SD native support. (You can Install Apps on SD card)

Super Fast UI speed (All menus opens super fast)

Nice graphic speed. 

And no lag in browsing big sites with Opera Mobile.

Flash Player support, download here (Remember you can only play flash on default browser. Opera Mobile is not supported. And you can only see flash on websites, Cannot play YouTube videos, Browser Crashes while playing YouTube Videos)

If you liked CM7 than proceed to next step.

OK first flash your phone to unofficial Gingerbread here

Why I have to fall back to Unofficial Gingerbead?

Because If you flash CM7 on Official DDQ5 than 3G will not work.

OK If you have finished falling back than proceed to next stage.

Now download Clockwork Recovery here (Put Zip in SD Card)

Now go to Recovery Mode.

LOL... How?

*  Turn Off your Phone!

* Wait for phone to shut down!

* Now Press Home button (Keep it pressed).

* While you have pressing Home button, Press Power Button too.

* As your phone blinks Leave both buttons.

Now your phone is in Recovery Mode. (Select option "Apply Update from SD Card" by scrolling via Volume buttons)

Give OK with Home Button.

Now locate "Clockwork Recovery.zip" by volume and Home Buttons.

Now wait till it gets Installed.

Shut Down Phone.

Download CM7 here (Its Kooper-Kang, Most bugs are fixed) (Save it on SD Card)

Download all fixes like (Video Playback Fix, Headset Fix, ect) here (Everything is fixed) Its stable.

(Save both Zips on SD Card)

Again Start Phone in Recovery Mode. (This Time you will notice all menus are different)

Select Install zip from SD card. (Remember :- Use Volume buttons for Scrolling and Home button as OK)

Select first option.

Now locate the downloaded CM7 zip and Install it.

Take a quick Nap till its getting Installed. (Zzz)

Again Select "Install zip from SD card." Locate The Fixes and Install it.

Reboot after CM7 gets Installed.

(Caution :- Your phone will not get bricked)