TurboCache true size

I have been asked by a friend to see if he has been cheated in his new computer's graphic card. The computer is under warranty, and the inside is blocked by sticker. Is there a way to find out the true memory of his turbo cache memory size, because the vendor says it is 256 MB, which is not very convincing in my point of view for his 7300 GS graphics card. From what I have googled around, Vista can display the information I am searching for, but XP cannot. What other software can be out there to give me such an information?
I have asked the shop he bought the computer in, as a "new" customer, and the dealer was eagerly trying to convince me there were true 256 MB of memory ON THE CARD. He even showed me the card on an XP computer on the tabs. Now, manufacturers sometimes go through lengths of trouble just to hide the true memory size, so he might not know himself, or is just a plain bastard. I am going to install Vista if I cannot find any other software, but, is there anything for this purpose that does not take up few hours of my life and few GB of hdd space? And, what should the keywords be in a google search of such kind, because I tried my luck for at least half an hour in vain.

You could use a program called HWINFO32 to list the hardware and specifications without opening your box.
There are several others out there also.

Grab a demo copy of Everest and it will tell you more than what you need to know. But turbocache is bad as others have said because you compete with the CPU for main ram access. Anyhow this is some of what you can expect Everest to give you.

--------[ EVEREST Ultimate Edition 2006 (c) 2003-2007 Lavalys, Inc. ]---------------------------------------------------

Version EVEREST v3.50
Benchmark Module 2.1.169.0
Homepage http://www.lavalys.com/
Report Type Quick Report
Computer Testdeck-1
Generator Azimuth40
Operating System Microsoft Windows Vista Ultimate 6.0.6000 (Vista Retail)
Date 2007-08-23
Time 04:40


--------[ GPU ]---------------------------------------------------------------------------------------------------------



[ AGP 8x: XFX GeForce 6800 XT AGP ]

Graphics Processor Properties:
Video Adapter XFX GeForce 6800 XT AGP
BIOS Version 5.41.02.47.0E
GPU Code Name NV41AGP
PCI Device 10DE-00F6 / 1682-217E
Transistors 202 million
Process Technology 0.13 um
Bus Type AGP 8x @ 8x
Memory Size 256 MB
GPU Clock 351 MHz (original: 350 MHz)
RAMDAC Clock 400 MHz
Pixel Pipelines 12
TMU Per Pipeline 1
Vertex Shaders 6 (v3.0)
Pixel Shaders 12 (v3.0)
DirectX Hardware Support DirectX v9.0c
Pixel Fillrate 4212 MPixel/s
Texel Fillrate 4212 MTexel/s

Memory Bus Properties:
Bus Type GDDR3
Bus Width 256-bit
Real Clock 501 MHz (DDR) (original: 500 MHz)
Effective Clock 1002 MHz
Bandwidth 31.3 GB/s

Miscellaneous:
Fan Speed 100%

Graphics Processor Manufacturer:
Company Name NVIDIA Corporation
Product Information http://www.nvidia.com/page/products.html
Driver Download http://www.nvidia.com/content/drivers/drivers.asp
Driver Update http://driveragent.com?ref=59

nVIDIA GPU Registers:
nv-000000 441300A2
nv-001800 00C310DE
nv-0010F0 00007FFF
nv-001218 F0000101
nv-001540 001F0F05
nv-0015F4 80000000
nv-0015F8 000000FF
nv-004000 8000011C
nv-004004 011F1A02
nv-004008 01C00000
nv-00400C 00000000
nv-004018 0005001C
nv-00401C 07011104
nv-004020 E030001C
nv-004024 1B040B02
nv-004028 80000000
nv-00402C E030001C
nv-00C040 3C03C233
nv-100000 00000000
nv-100200 43002023
nv-10020C 10000000
nv-100474 11110004
nv-101000 A34EF897
nv-680500 00000000
nv-680504 00000000
nv-680570 00000000
nv-680574 00000000
nv-68057C 80000701