I thought there was an install utility that was floppy 1.44mb sized for those intel chipsets?
You could always do the "XP/Vista Already Installed" method, I've done it on P965's and P35's...the only thing I didn't like is since I have an SATA DVD it wouldn't boot to disc in ACHI mode...so maybe use the JMB SATA for the HDD or the DVD if that's your case, and swap whatever one you have the DVD hooked to to IDE mode.
I really saw no reason to go ACHI in XP or Vista, I tried it on a 7200.9 Seagate 'Cuda 500GB and a newer WD Caviar SE16 640GB (dual platter one, kickass drive btw), I saw no speed difference, no difference in multitasking, and like I said the only thing I noticed was an annoyance when I wanted to load-up Memtest or something for stress testing my OC's before hitting Windows...I couldn't boot on CD anymore...quite aggrivating!
I run my HDD's on IDE, my performance on both is on-par for what they should be, about 95MB/S in HDTACH for the WD and 53MB/s for the Seagate 7200.9 (last gen before perpindicular tech...). I can tell you from experience it does little to none for me, I mostly game, watch movies, listen to tunes, do some file converting, some FAH, web browsing, etc...
Here is the link I used for XP:
Here is the link I used for Vista:
Both found quickly in Google and do work, otherwise you can't get into OS setting ACHI mode w/BSOD's or crashes shortly after load screen. Maybe this is why I didn't notice anything special, but I doubt it. Hope these work for ya!