For me 10k worked fine.
Are you sure the problem is in the PC->PIC path?
The edges of the signal could be a bit different now,
so when your receive code was critical it could be just-off now.
maybe have the PIC copy the in pin to the out pin in a loop
and see whether you get an echo on the PC?
Wouter.

----------
> From: Craig Lee <clee@ATTCANADA.NET>
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Serial interface problem
> Date: Thursday, May 06, 1999 02:02
>
> I am puzzled why when I try to interface the
> transmit data line from an rs232 interface to
> a pic through a 10k resistor to RA1 why it
> ceases to operate.  On a scope, the levels are
> a nice 5-0.
>
> Works fine with a max232.  The only changes
> I've made are to replace the max232 chip
> with a 10k, and change my Rxdata define from
> RA1 to !RA1.
>
> I'm sure someone else has ran into this one.
>
> Craig