Dell now offers the option to select Penryn CPUs in the Inspiron 1420 & Inspiron 1720 models. The 1420 can handle up to Core 2 Duo T8300 (2.4GHz/800Mhz FSB/3MB cache) whereas the 1720 features option for both - T8300 & T9300 (2.5GHz/800Mhz FSB/6MB cache) Penryn processors.

The T8300 is a $225 upgrade on the Inspiron 1420 (base config of $699). Similarly, on the $849 Inspiron 1720 - T8300 and T9300 option is available for additional $225 & $350 respectively. It's interesting to note that Inspiron 1525 range hasn't been updated with an option for Penryn.