Find available space in a file group on SQL Server

Yesterday I attempted to add a new index to my development database and it returned an error stating that the file group didn't have enough disk space.  After a bit of searching I discovered the following code that would show the Total allocated and free MB worth of disk space in each file group.

-- check to make sure temp tables don't exist
IF (OBJECT_ID('tempdb..#fileStats') IS NOT NULL)
            drop table #fileStats

IF (OBJECT_ID('tempdb..#fileGroup') IS NOT NULL)
            drop table #fileGroup


-- Create temporary holding tables
create table #fileStats
    (
        fileID          int,
        fileGroup       int,
        totalExtents    int,
        usedExtents     int,
        name            varchar(255),
        fileName        varchar(1000)
    )

create table #fileGroup
    (
        groupid         int,
        groupname       varchar(256)
    )


-- Insert 
insert into #fileStats
    exec ('DBCC showfilestats with no_infomsgs')

-- Insert
insert into #fileGroup
    select  groupid, groupname
    from sysfilegroups

-- Get resulting set
-- size returned from showfilestats is in Extents -> 1 Extent is 64kb
-- so we need to multiply the sum of TotalExtents by 64 and then divide by 1024 to get
-- the actual MB

select  g.groupname,
        sum(TotalExtents)*64.0/1024                         AS [Total MB],
        sum((TotalExtents - UsedExtents) * 64.0 / 1024.0)   AS [Free MB]

    from #filestats     AS f
        join #filegroup AS g
            on f.filegroup = g.groupid

group by g.groupname


-- Clean up after self
drop table #filestats
drop table #filegroup

set nocount off