xp_dirtree or dir \b or xp_fileexist

all of them reside in master.dbo.

exec master.dbo.xp_dirtree 'C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL', 1, 0 — get directories
exec master.dbo.xp_dirtree 'C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL', 0, 1 — get files