SELECT @@SERVERNAME AS SqlServerInstance,
db.name AS DatabaseName,
SUM(CASE WHEN af.groupid = 0 THEN 0 ELSE f.size / 128.0E END) AS DatabaseSize,
SUM(CASE WHEN af.groupid = 0 THEN af.size / 128.0E ELSE 0 END) AS LogSize,
SUM(af.size / 128.0E) AS TotalSize
FROM master..sysdatabases AS db
INNER JOIN master..sysaltfiles AS af ON af.[dbid] = db.[dbid]
WHERE db.name NOT IN ('distribution', 'Resource', 'master', 'tempdb', 'model', 'msdb') -- System databases
AND db.name NOT IN ('Northwind', 'pubs', 'AdventureWorks', 'AdventureWorksDW') -- Sample databases
GROUP BY db.name