What are the approximate dimensions of your present power supply? These are all standard size, but some pre-built PC's have off-size power supplies.
This is a good buy but it's slightly over budget.
Newegg.com - CORSAIR CMPSU-450VX 450W ATX12V V2.2 80 PLUS Certified Active PFC Compatible with Core i7 Power Supply - Power Supplies
this would be my next choice
Newegg.com - FSP Group SAGA+ 450R 450W ATX12V Power Supply - Power Supplies
I'd cross my fingers with this one.
Newegg.com - Rosewill Stallion Series RD450-2-SB 450W ATX V2.2 Power Supply - Power Supplies
This is a good buy but it's slightly over budget.
Newegg.com - CORSAIR CMPSU-450VX 450W ATX12V V2.2 80 PLUS Certified Active PFC Compatible with Core i7 Power Supply - Power Supplies
this would be my next choice
Newegg.com - FSP Group SAGA+ 450R 450W ATX12V Power Supply - Power Supplies
I'd cross my fingers with this one.
Newegg.com - Rosewill Stallion Series RD450-2-SB 450W ATX V2.2 Power Supply - Power Supplies