It's such a simple item, yet makes a huge difference and saves a whole lot of cash, if you're able to fix the phone yourself. Found a brilliant video on Youtube that talks you through the whole process, right through to putting back the last screw and switching the phone on again at the end (it was a relief to see mine turn on an operate as normal again!).
Did think I'd made a mess of it at one point as I had the old front glass just shattering away as I tried to lever it off, only to realise that I wasn't going down far enough with the adhesive layer on the old screen - on looking closer at the video, I worked out what I was doing.
Watch the video and you'll see how easy it is...
("how to change replace the Digitizer screen on a Samsung Galaxy Ace S5830" from Sandwell Mobiles)