I agree with The Duke. The 2800+ 754 Sempron has 256L2 Cache and is an excellent value processor. These processors have 64bit extensions and are of the Venice core which means they run cool and have Streaming SIMD 3 instructions.
I live in Canada and deal mostly with NCIX.com (wife is married to an owner). They have good prices and you can reach them via phone and e-mail. They always answer.
You might wish to look at the ASROCK K8NF4G-SATA2 board. It boasts onboard VGA of the NV44 6100 (DirectX 9 and Pixel Shader 3) and the NForce4 which rocks for a 754 and means you get dual channel as well as 7 channel surround sound. Also has a PCI-e 16 slot.
CPU - AMD Sempron 64BIT 2800+ 256k Cache
Board - K8NF4G-SATA2
RAM - Samsung 512DDR 400 PC3200 (will take 2.5-3-3-7 @ 200MHz fsb)
Hard Drive: Maxtor Diamond Max 10 200GB Drive
Case: Logisys with 450watt psu (Cheap psu but for these components it will make the grade)
LG GSA-4167B DVD Burner
Processor = $99.47
Board = $76.68
Samsung DDR400 PC3200 512MB = $47.99
Maxtor 200GB (3 year warranty) 7,200 HDD = $111.09
Logisys Case with 450Watt PSU = $51.45
LG Burner = $56.24
Total = $442.84
Tax = $62.00
Total with tax = $504.84
Review on the board:
Edit: You might wish to give him your box and take this one as even the onboard vga kicks that HP around the block and you can always install a better PCI-e card (and PSU) later.