SQL Server : Retrieve memory details from the OS
select
total_physical_memory_kb,
available_physical_memory_kb,
system_cache_kb,
system_high_memory_signal_state,
system_low_memory_signal_state,
system_memory_state_desc as system_memory_state
from
sys.dm_os_sys_memory
Check out BOL (Books Online), there are other details as well, but this is the one I use to get a quick look at the overall state of the system memory.