Windows 7 - Does win 7 64 use more resources?

I just installed windows 7 and tried playing assassin's creed(steam had a deal on it !)

anyway, I'm running a quad core Intel 9450(I think) with 4gb of RAM(good quality OCZ/corsair ones) I mixed 2 brands, but the numbers are the same according to the package. I'm on a HD 4870.

When I play this game on XP 32, I get no lag or w/e, but when I started this game in win 7, I got a pop up asking me if I wanted to turn off aero and go to basic windows 7 theme to save resources cause I was low. And there was some really minor performance issues...

Then I went on facebook to play typing maniac, and I think thats a bit choppy too when the words start calling faster....

Do I need to update my video card? I was under the impression that it updates everything for you through windows update or installs drivers for you automatically... or does win 7 just use more resources? I thought it was supposed to make better use of things and run on less

I would first make sure you are using the best x64 driver for your video card from the manufacturers site.

As ususal the drivers that come with windows are meant to work as well as possible while being as stable and as /small/ as possible so they may not be the "best"
for gaming.

Also, to add on to fseal's post.

Yes Windows 7 uses a bit more resources then Windows XP, although it should be expected that 8 year old operating systems use less resources then the newer ones.

it depends which Edition. my friend tried to use Ultimate on Pentium 4 and he performance is bad. he then switched to Home Premium, everything is perfect.

That would be an incorrect assessment.

Using Vista or Win 7 on an old CPU like that is kind of stupid and pointless.

hmmm...would i have to use driver cleaner to delete the driver that came with windows and download one from ATI? o.0

I think I found my problem...I just downloaded something to show system stats and my PSU is always at 100% from the moment windows starts. This video card is eating up too much power...I guess 500w isn't enough =[

Ah yeah, it's not /just/ the wattage it's how much power is available on each connector and at each V.

Most cards now say somthing like "Requires 40 amps of 12V power." You have to make sure the PSU can do that an a bit more.