Generate a sequnce Number with String in SQL Server 2008r2

Hi All,

I need to generate a sequence number like below.

EmpId                      Ename

CT001                      John

CT002                      Mike

AB003                      Shaun

'                                  '

'                                  '

'                                  '

TB010                      Kate

When i create the new employee in my application EmpId should be genereate the above process.

How can i do this in SQL Server 2008 r2.

Thanks

Madhava