lemming:
I am running a 328 using the internal oscillator at 8 Mhz dividing down to 1 Mhz as I am using a 3.3v power source.
That is not necessary. 3.3 volts / 8 MHz is well within specifications.
I know that to use serial (UART) communications with this setup, I have to use a slow baud rate due to the inaccuracy of the internal clock.
Slow baud rates don't necessarily help. You're exchanging thin badly timed bits for fat badly timed bits. They're just as badly timed no matter how wide they are.
For a given temperature / voltage the internal oscillator can be tuned to within 1% which is more than good enough for serial communications.