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