Hi Apple
If you are thinking of doing multilevel regression you should definitely use a decent statistical package. MLWin is the specialist software for this and can deal with all the possible regression types. However, if it is just linear multilevel regression you can use Stata or SAS. I'm sure it is possible in SPSS too but I haven't done it in that. It's really important to make sure that you enter the data in a format that will make it easy for you to analyse if you don't want to faf around with rearranging the data in a software that is new to you. Try getting the manual or looking at the online help for the package you will use and how their data is organised in their multilevel regression examples. Also, you may prefer putting the data directly into the analysis package as opposed to via Excel as you can then add value labels and variable descriptions, etc.
Good luck