Just get InstantCake (6.2) for your DVR40 and use one large drive in your new TiVo (put the original away in a safe place). Since you don't want any "nifty" features (not using PTVnet), you'll need to do a "Clear and Delete Everything" after your TiVo boots after inserting the new drive.

I recommend you go ahead and install PTVnet, as that will give you networking options and eliminate the need for a "Clear and Delete."

http://www.dvrplayground.com/forum/th...

TechLore Blog

HR10-250, Samsung SIR-S4120R, SIR-S4080R, 2 Philips DSR704s (one connected to a Slingbox A/V). One box used the "Zipper"; rest used PTVnet to enable networking features.