Both are excellent cameras, but I would ask what you will be using it for....do you want something more portable and easy to throw in a pocket or do you want something that has ALL the bells and whistles and will take amazing large photos? Don't get me wrong here though, I own the W-1 and it will print nicely at 13"x19" no problem and has a lot of nice features.
Here are a few things off the top of my head to look at between the 2:
Size: W-1 is small, V-3 is large.
Resolution: 5.1 v 7.1.....a lot v. a whole lot...again comes down to how much you will be cropping and how large you want to print.
Features: A few things the W-1 doesn't have that the V-3 does- exposure bracketing, use of CF and Sony cards, better optical zoom, hot shoe, added modes for focusing, light metering, white balance, etc.
Price: $349 v. $699 at Best Buy, $329 v. $599 online.
Ok, so here's my final answer...go with the V-3 if you really want to explore the artistic side of photography, doing landscapes, portraits, etc etc. Go with the W-1 as a great all around camera for carrying around, taking day to day shots, but still able to capture a nice sunset or whatever, etc.
Hope that helps, and feel free to PM me if you have any questions, I know both cameras inside and out (I sell and use them every day)...
Oh, on the ISO issue, higher ISO numbers are nice, but with digital photography, higher ISO's tend to have a lot of digital noise. The V-3 according to the industry has very low digital noise even at the higher ISO levels. So if you plan on shooting a lot indoors, at night, etc look at the V-3. But....my W-1 does a fine job in my critical opinion at ISO 400.