Iphone 3gs 'you are not subscribed to a mobile data service'?

I just got my dads old iphone 3gs unlocked from o2 i'm now on virgin but when i turn my Wi-Fi and go on to 3g i open the internet and it comes up with 'you are not subscribed to a mobile data service' my 3g is on and so is mobile data and ariplane mode is not on. I in the top lest corner i have full signal and it says 3g, does anyone know the problem and how to fix this!

Added (1). This sim i'm using now is a virgin one i've been using it in a blackberry, i'm on contract with the sim where i have internet, message and call times why isn't it letting me use it on this phone?

How to change a file saved as Itunes media player into MP4?

So I downloaded some episodes of the big bang theory from 4shared, and some of them I'm able to drag into itunes from the folder no problem, and download them onto my iphone, but others I can't. The only difference I can see is that the ones I'm able to drag into Itunes are saved as MP4s and those I can't were saved for Itunes Media player. Is there anyway I can convert those files into MP4 files so that I can drag it, or is there another way I can open it in itunes and put it on my phone? Also, for future reference, is there a different way I should save the files? Thanks!

Added (1). OOppps, I meant to say Itunes music player

Is is it possible to unlock an Iphone 4s?

I just wanted to know whether its possible to unlock an Iphone 4s, if its locked to either Vodaphone or Orange? Id like to change it to 02. Does anyone know if this is possible to do so in individual stores?

Is it normal that games have frame rate droppings?

Is it normal that (modern) games have frame rate issues? I played on my friend's Xbox 360 and he had similar frame droppings than I. Some games like GTA: IV and FEAR Files just didn't run verysmooth. I said about that and he answered it just lags a bit.

I don't remember anything like that while playing on Gamecube or PS2. Games from the older generations ran much smoother, I think. For me smooth frame rate is even more important than graphics. And btw, some games like GTA III and Temple Run Brave do lag on my Iphone 4S too.

So, please tell me: Is it normal that modern games have noticeable and annoying lag? How big drop in frame rate is "OK"?

I'm just worried that something is wrong with my hardware.

How to transfer all my contacts on iCloud back to my iphone?

Basically, something went wrong with my iphone. So i had to send it back and they would give me a new one. So i saved everything like my contacts on iCloud, and then I just didn't understand how I would transfer it all back on my new iphone. I'm kinda confused, so if you know, please help me!

Need my iPhone screen fixed?

I have an iPhone 5. Just cracked screen. Fml don't ask how. Apple will charge over $200 for a replacement. I'm just looking to get the screen replaced. I live in Waterbury CT. Can anyone help me out?