Well, like I said, I could be wrong. And it woudn't be the first time!

I'm somewhere in the middle. I have a system/application drive, everything gets installed there. But I hack/move my home directory (or Users, or whatever windows calls it) to the secondary drive, or even drive letter if it's one physical HD. For the simple reason that with windows, when you reinstall, you lose all the program config anyway, so they all need to get reinstalled. BUT, I'm very careful (well... normally =) to only keep data on the data drive. I also create swapfiles on both, although that's far less critical now-a-days.

Then, a clean install is simply formatting C:, and reinstalling. But all my data is safe.

And, email can be so critical, I don't even bother keeping it local. I use IMAP exclusively. Not only is it all stored on the server, but it's perfectly in sync if I login via the webmail client and read/delete/move emails around. IMAP is seriously the only way to go if you want to have a local client.

OK... back to diff'ing the latest de-interlacing source files... =/

And, for the record, I think the programs on a separate drive is more old school than newb. In the "old" days, moving the apps off from the system drive, especially onto a different hard drive, could make a huge difference. Not only because the app code wasn't on the main swapfile drive, but there was so little memory, and drives were so slow that it really did matter. When a super-fast drive was the 28ms version instead of the 40ms version, and the transfer rates were measured in KBs instead of GBs per second, and when SCSI was the by far preferred choice could it could enqueue multiple requests and service them even out of order whereas IDE (pffft, consumer stuff) couldn't even talk to two drives on the same channel at the same time. =)
We did everything we could to eke out every bit of performance.

I still remember when I gave up the ISDN internet line to go with a cable modem, and being amazed that I could download something from my home country of South Africa (I'm now in Canada) to my HD faster than I could off my first CD-ROM to my HD! It was a single speed, 150K/second.

Things sure have, and continue to, change at a remarkable rate.

Craig, you're right, it is an old school thing...newbies pick up on it not realizing it doesn't apply anymore. Extra drives are now used for RAID configurations or storage. Heck it seems everyone has a RAID system. It's like the huge number of pickup truck in the city where I live. Very few need a pickup truck, but it seems people want them anyway, and the bigger the better.

RAID used to be expensive, but now it's virtually free. My old SCSI controller card cost $1500, and my cheetah drives were very expensive also. Yet today I get a SATA controller that is RAID ready at no extra charge built into my motherboard.

And keeping email local...I can't even imagine a reason, unless you have a very unreliable connection. Even still, it should be backed up on the provider's server.