Have a look here: Adobe Forums: What PC to build?
Now this is for video editing. Your requirements for LR are much less, so take a specific look at the budget model. That should be more than enough for your purposes. Your suggested disk setup looks like overkill (yeah, coming from me, that is hardly possible, but I mean it). You could shave off sizable $$ by going for a single Velociraptor and using simple Samsung Spinpoint F3's instead.
Thanks Harm, I'll take a look at that post.
Curious why you think it's overkill? I read somewhere that you do not want to partition. I think 300gb should be enough to install the OS plus Lightroom 3 and a few other small apps but If I install them all on one drive then when it comes time to format my main drive(OS) it becomes a hassle.
A 300 GB OS disk will normally never be filled with more than say 50 GB, even on pretty loaded systems, like the full CS4 & CS5 MC, numerous plug-ins, etc. My background is more in video editing and that is where the recommendations are directed to, but look here for further info: Adobe Forums: Generic Guideline for Disk Setup
So was I right when I read do not partition? if thats bad info then great I'll get the 600gb velociraptor partition it with say 200 for OS and 400gb for LR 3
then 1TB samsung for data (photos) and a 2nd samsung 1TB for Backup plus my existing fantom 1TB external drive for backup.
Partitioning is never advised. It will not increase performance, only increase wear and tear.