Thanks for the reply.

I have a little test setup on breadboard with a MAX233 talking to a 16f628 so that I can use the Microcode Studio ICD, which works a treat.

The 16f628 doesn't support a bootloader though. What I'm thinking is... Can I 'lie' to Picstart to download a bootloader hex file into the 18f2550, then simply use the ICD to program the 18f2550 in circuit without the need for Picstart???

Or am I mad?

Giulio