Scores have gone down in newer builds to take into account hardware of the future. What you got to remember is windows seven is not even released yet so if you had old hardware producing top results then how will that account for future hardware? Exactly.
And the answer to will you see lower fps then the answer will be a definate no.
Vista is older than seven so it will produce higher scores than seven but have no bearing on your performance.
Looking at your system, you shouldn't expect to have considerably higher scores than that. Keep in mind, the WEI is not an effective benchmark and with 7127 (both x32 and x64) contain additional changes, including how the WEI is calculated;
7127 Partial Changelog;
new memtest for x86 and x64
changes to migration tools/functions
changes to hardware compatibility functions
install.wim changed from 2.115GB to 2.229GB (x86) / 2.772GB to 2.969GB (x64) [most likely drivers added along with changes to system ident/test tools]
changes to restore functions (rollback.exe and others)
a few .dll's are now gone
testplugin.dll added
changes to system rating score
lots of little changes but nothing groundbreaking. Most of the changes look to be all about compatibility and adding new products to win7 support (i.e. new laptops that are about to be released that are not on the market yet)
That said, your graphics performance does seem low, you might try updating your driver to WHQL.
My Computer
At a glance
Windows 7 Home Premium x64Intel QX9650 Extreme 4.0 GHz8GB (4x2) Corsair Dominator DDR32x Radeon R390X [8GB]
Computer type
PC/Desktop
Computer Manufacturer/Model Number
Custom Build/Mod
OS
Windows 7 Home Premium x64
CPU
Intel QX9650 Extreme 4.0 GHz
Motherboard
ASUS Rampage Extreme Rev2
Memory
8GB (4x2) Corsair Dominator DDR3
Graphics Card(s)
2x Radeon R390X [8GB]
Sound Card
SupremeFX X-Fi
Monitor(s) Displays
Dell 2408WFP 26" Panel
Screen Resolution
1920x1200
Hard Drives
4x WD 2TB (8TB+ Total)
2x Crucial SSD 128GB (RAID-0)
1x LG Blu-ray read/write
1x Phillips LightScribe DVD read/write