Given a SQL2008 table structure:

Id, ColumnId, RowId
1 1 1
2 1 2
3 2 1
4 2 2

How do I convert it to:

Row, Column1 Column2
1 1 3
2 2 4

In case it's relevant the values are all GUIDS rather than ints and there will be more columns (and, obviously, rows)
(Sorry about the spacing....)