Will this work with GTA 4 PC? And also how to do I downgrade from Windows 7 Home to Vista Home?

Will this work with GTA 4 PC? And also how to do I downgrade from Windows 7 Home to Vista Home?

Operating System: Genuine Windows 7 Home Premium with Service Pack 1 64bit
Platform: 2nd generation Intel Core i3 processor
Chipset: Intel HM65 Express Chipset
Processor Name: Intel Core i3-2330M Processor
Power and Performance: Enhanced Intel SpeedStep Technology, HT Technology Supported
Processor Speed (GHz): 2.20
L3 Cache (MB): 3
Number of Cores: 2
Power and Performance: Enhanced Intel SpeedStep Technology, HT Technology Supported
Memory Size (GB): 4
Memory Type: PC3-10600
Memory Specification: DDR3 SDRAM
Memory Speed (MHz): 1333
Memory Composition: 4 GB (SO-DIMM) x 1
Max. Supported Memory: 8 GB
Cover Colour: Black
Hard Drive Type: Serial ATA
Hard Drive Capacity: 320 GB
Optical Drive Type: DVD SuperMulti Drive
Read: CD 24x, CD-R 24x, CD-RW 24x, DVD 8x, DVD-R DL 8x, DVD-R 8x, DVD-RW 8x, DVD+R DL 8x, DVD+R 8x, DVD+RW 8x, DVD-RAM 5x
Write: CD-R 24x, CD-RW 10x, DVD-R DL 6x, DVD-R 8x, DVD-RW 6x, DVD+R DL 6x, DVD+R 8x, DVD+RW 8x, DVD-RAM 5x
Hard Drive Speed (rpm): 5400
Screen Type: VAIO Display
Diagonal Size (cm): 39.5 cm
Diagonal Size (in): 15.5 inch
Resolution Name: WXGA
Resolution: 1366 x 768
Aspect Ratio: Wide (16:9)
Max Resolution External Display: 1920 x 1200
Graphic Card Name: Intel HD Graphics 3000
Video RAM memory size: -
Total Graphics Memory: Total Available Graphics Memory refers to the classification of graphics memory, which varies depending on the operating condition, version of device driver and system memory size
Interfaces: 4 x USB 2.0 (Type A Connector), Memory Stick Slot, Microphone, Headphone, SD Card Slot, HDMI Out, VGA
Ethernet (RJ-45 Direct Port): Yes
Ethernet Type: 1000BASE-T/100BASE-TX/10BASE-T
Wireless LAN: Yes
Wireless LAN Type: IEEE 802.11b/g/n
Wireless LAN Max. Data Rate (Mbps): 150 Mbps (RX), 150 Mbps (TX)
Bluetooth: Yes
Bluetooth Version: Bluetooth standard Ver. 3.0 + HS
Bluetooth Range (m): max. 10
Bluetooth Max. Data Rate (Mbps): 24
Built-in Speakers: Internal, Stereo speakers
Built-in Microphone: Internal, Monaural microphone
Built-in Camera: Web camera
Effective Pixels: 640 x 480
Image Sensor (Mega Pixels): 0.3
Numeric Keypad: Yes
Touch Pad: Yes
Stroke (mm): 2.0
Key Pitch (mm): 19.05
Other Features: Instant On (Quick Web Access)
Special Buttons: Assist Button, WEB Button, VAIO Button, Wireless switch Assist, Web, VAIO, Wireless switch
Auto Luminance Control: -
Kensington Lock: Yes
Supplied Software-Solution Portal: VAIO Gate
Supplied Software-Photo/Video: PMB VAIO Edition
Supplied Software-Multimedia: Media Gallery
Supplied Software-Support: VAIO Care
Supplied Software-Utilities: VAIO Transfer Support, VAIO Update, VAIO Smart network
Supplied Software-Office Application: Office 2010 preloaded – buy Office 2010 product key for full activation, Windows Live Essentials 2011, Adobe Reader 10
Supplied Software-Security & Backup: McAfee Internet Security 30 day subscription
Supplied Software-SONY Tools: Remote Keyboard, Remote Play with PlayStation 3
Supplied Software-Internet: Internet Explorer 9
Supplied Accesories: AC Adapter VGP-AC19V33, Power Cord, Documentation Pack, VAIO International Repair Service Guide
Dimensions: 369.8 x 248.4 x 31.3 mm
Weight (kg): 2.7
Primary Battery: VGP-BPS26
Weight (g): 305
Battery Type: Lithium ion
Battery Life time (hours): 4
Battery Charging time (hours): 3

Please also tell me how to downgrade Windows 7 Home to Windows Vista home? Dont bother posting shi**y comments saying WHY DOWNGRADE TO VISTA?? I need to because I need to downgrade the operating system so It will work with GTA 4 PC. PLEASE HELP!