|Separating the data is easy:|
Select Column A
Click on Data...Text to Columns...Delimited...Next
Put a ; in the Other box and click finish.
Your description regarding placing the data in B1:B4 confuses me a bit.
You said: I need to do this for every row in Column A.
If the four parts of A1 will end up in B1:B4, where will the fours parts of A2 end up? Obviously they can't end up in B2:B5, so where will they go?