With all the power saver's disabled and the screen at full brightness, that's a very respectable 80 minutes. Many laptops will not give you one hour at full tilt. You'll have to find and read reviews about that.
As to the 88% mark after leaving it to charge overnight. It's time to call Sony and see if they'll repair this under warranty. Unlike desktops, there is little that we can adjust or replace.
Short answers:
1.Is the wireless card contributing to the battery drain?
Yes.
2.Shouldn't the battery show 100% when I boot up (It usually charges overnight).
All mine do. Your laptop or battery is broken in some way. Call Sony now before you get to pay for the repair.
3.Is there any diagnostic software than can check battery integrity?
Not that is available to you. A real problem is that a proper battery tester cost us about 4 thousand dollars for the lab. Service shops will not expend this amount and you won't pay for the battery to be tested. Economics comes into play in that the replacement batteries tend to cost under 200.
4. (Most important). Or is this performance typical of a 16" notebook running desktop P4 CPU as opposed to Pentium Centrino or Pentium mobile flavors?
I'll write yes (considering your disabling of features), but will not supply web-links to such reviews. Just use my year to year experience as a basis for my reply. I hope this is ok by you.
Bob
We purchased a VAIO GRV600 Series this summer (P4 2.6Ghz, 512MB RAM, 16" display, DVD Burner). Additionally, I've slapped in a Linksys 802.11g wireless card to hook it up to the house network.
Now, I've intentionally disabled most of the power saving features except hibernate, and I am using almost the fullest screen brightness. But still, the battery is completely spent after about 1 hour and 20 minutes. For the most part, I'm only web surfing.
Additionally, whenever I boot up the notebook and check the battery setting, it always shows "88%" charged.
A few questions:
1.Is the wireless card contributing to the battery drain?
2.Shouldn't the battery show 100% when I boot up (It usually charges overnight).
3.Is there any diagnostic software than can check battery integrity?
4. (Most important). Or is this performance typical of a 16" notebook running desktop P4 CPU as opposed to Pentium Centrino or Pentium mobile flavors?
Thanks,
W!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic