System Manufacturer/Model Number Dell OS Windows 7 Home Edition x64 CPU Studio Phenom II X4 945 (3.0GHz) Memory 8GB DDR3 SDRAM,1333MHz, 4x2GB Graphics Card AMD Radeon HD 6450 1GB DDR3 Monitor(s) Displays Dell EH910 VGA Screen Resolution 1366x768
Keyboard Dell Consumer Multimedia Keyboard Mouse Dell USB 6-Button Laser Mouse Case Studio XPS 7100 Minitower Hard Drives 1TB Serial ATA 2 Hard Drive 7200 RPM Internet Speed 56MBPS
System Manufacturer/Model Number Dell OS Windows 7 Home Edition x64 CPU Studio Phenom II X4 945 (3.0GHz) Memory 8GB DDR3 SDRAM,1333MHz, 4x2GB Graphics Card AMD Radeon HD 6450 1GB DDR3 Monitor(s) Displays Dell EH910 VGA Screen Resolution 1366x768
Keyboard Dell Consumer Multimedia Keyboard Mouse Dell USB 6-Button Laser Mouse Case Studio XPS 7100 Minitower Hard Drives 1TB Serial ATA 2 Hard Drive 7200 RPM Internet Speed 56MBPS
Generally speaking, any high school or university will qualify you and I've no doubt Microsoft would soon tell you if the establishment didn't fulfil their criteria for student software.
System Manufacturer/Model Number HP Pavilion Elite 495UK OS Windows 7 Ultimate SP1 64-Bit CPU Intel Core i7 870 @ 2.93GHz Motherboard MSI 2A9C (CPU1) Memory 8Gb Dual-Channel DDR3 @ 664MHz Graphics Card nVidia GeForce GTX 460 1024MB dedicated RAM Sound Card Realtek HD Audio Monitor(s) Displays HP2310i Screen Resolution 1920 x 1080
Keyboard Logitech K750 solar-powered keyboard Mouse Logitech Wireless M180 mouse PSU 460W Case HP Elite Cooling Air cooled Hard Drives 1x1954GB Hitachi HDS22020ALA 330 (RAID), 1x1954GB Hitachi External for backup and storage Internet Speed 2Mb Other Info Pure Avanti Flow Internet Radio with iPod Dock, 64Gb iPod, HP USB Speakers, Sony MDR-V500 Headphones, Sony Vaio F-Series Laptop
System Manufacturer/Model Number Dell OS Windows 7 Home Edition x64 CPU Studio Phenom II X4 945 (3.0GHz) Memory 8GB DDR3 SDRAM,1333MHz, 4x2GB Graphics Card AMD Radeon HD 6450 1GB DDR3 Monitor(s) Displays Dell EH910 VGA Screen Resolution 1366x768
Keyboard Dell Consumer Multimedia Keyboard Mouse Dell USB 6-Button Laser Mouse Case Studio XPS 7100 Minitower Hard Drives 1TB Serial ATA 2 Hard Drive 7200 RPM Internet Speed 56MBPS
Contact Avast Support to ask for help reactivating your paid copy. In the future always back up Product Keys you pay for.
In the future audit your previous installation using Belarc Advisor as given in the steps I linked to get a perfect Clean Reinstall Windows 7 Factory OEM so you have a printout of all of your installed Product Keys.
System Manufacturer/Model Number Dell OS Windows 7 Home Edition x64 CPU Studio Phenom II X4 945 (3.0GHz) Memory 8GB DDR3 SDRAM,1333MHz, 4x2GB Graphics Card AMD Radeon HD 6450 1GB DDR3 Monitor(s) Displays Dell EH910 VGA Screen Resolution 1366x768
Keyboard Dell Consumer Multimedia Keyboard Mouse Dell USB 6-Button Laser Mouse Case Studio XPS 7100 Minitower Hard Drives 1TB Serial ATA 2 Hard Drive 7200 RPM Internet Speed 56MBPS