If you want to see where the computers stand based on current uptime, that's easy enough to do. If somebody restarts their computer at the start and end of every day, though, the current uptime won't show you that it was left on for 24h.
SELECT Top 1000000
  tblAssets.AssetID,
  tblAssets.AssetName,
  tsysAssetTypes.AssetTypename,
  tsysAssetTypes.AssetTypeIcon10 AS icon,
  tblAssets.IPAddress,
  tblAssets.Lastseen,
  tblAssets.Lasttried,
  DateAdd(second, 0 - tblAssets.Uptime, tblAssets.Lastseen) AS LastBoot,
  Convert(Decimal(6,2),tblAssets.Uptime / 60 / 60 / 24) AS DaysUp,
  Convert(VARCHAR(12),Floor(tblAssets.Uptime / 60 / 60 / 24)) + ' days, '
    + Right('0' + Convert(VARCHAR(12),Floor(tblAssets.Uptime / 60 / 60 % 24)), 2) + ':'
    + Right('0' + Convert(VARCHAR( 2),Floor(tblAssets.Uptime / 60 % 60)), 2) + ':'
    + Right('0' + Convert(VARCHAR( 2),Floor(tblAssets.Uptime % 60)), 2) AS DaysUpPretty
FROM
  tblAssets
  INNER JOIN tblAssetCustom ON tblAssets.AssetID = tblAssetCustom.AssetID
  INNER JOIN tsysAssetTypes ON tsysAssetTypes.AssetType = tblAssets.Assettype
  INNER JOIN tblComputersystem ON tblAssets.AssetID = tblComputersystem.AssetID
WHERE
  tblAssetCustom.State = 1
  AND DateDiff(d, tblAssets.Lastseen, GetDate()) < 8  -- not interested in machines not seen within a week
  AND tblComputersystem.Domainrole < 2                -- not interested in servers (>1)
ORDER BY
  tblAssets.Uptime Desc
Probably more useful to you would be something similar to what we see in the uptime calendar that we see on the asset summary page. I believe I read in another thread that being able to report on something like that is a wishlist item.