I already have the chip in (xecuter 2.3lite). Can I go ahead and put the new hard drive in and then flash it with 4977 or do I need to flash it, then put the new HD in? I'd appreciate any help you can give me.

Also, can Slayers 2.5 now flash the bios with 4977 when the cromwell screen comes up. It seemed like it said it would in the readme.

yes slayer can, and you need to put the hd after the chip is installed since you cant boot a blank hd with a normal xbox

I think slayers can flash your chip when cromwell comes up, but if you're gonna flash your chip, use a newer bios. the 4977 bios is pretty old. The latest is 4981.