Vanilla query to get you started.
SELECT Top 1000000
tblAssets.AssetID,
tblAssets.AssetName,
tsysAssetTypes.AssetTypename,
tsysAssetTypes.AssetTypeIcon10 As icon,
tblAssets.IPAddress,
tblAssets.Lastseen,
tblAssets.Lasttried,
tblAssetCustom.PurchaseDate,
DateDiff(dd, tblAssetCustom.PurchaseDate, GetDate()) / 365.25 As Age
FROM
tblAssets
Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
Inner Join tsysAssetTypes On tsysAssetTypes.AssetType = tblAssets.Assettype
WHERE
tblAssetCustom.State = 1 -- active assets
AND tblAssets.AssetType = -1 -- only Windows assets
AND DateDiff(dd, tblAssetCustom.PurchaseDate, GetDate()) / 365.25 < 4 -- less than 4y old
ORDER BY
tblAssetCustom.PurchaseDate