X Fi Mb Serial I Would Like To Compare 2 Computers?

I would like to compare 2 computers? - x fi mb serial

Computer # 1 --

Dell Dimension XPS 600 Intel Pentium D 820 (2.8 GHz) Dual-Core W
1 GB DDR2 SDRAM at 667 MHz
256MB Nvidia GeForce 6800 graphics card
160 GB Serial ATA NCQ Hard Drive (7200)
16x DVD-ROM and 16X DVD + /-RW
PCI-X-Fi Sound Card
Microsoft Windows XP Media Center Edition 2005

Team # 2 --

Dell XPS 630i, Intel Core 2 Q9300 (2.5GHz, 1333FSB) w / Quad Core Technology and 6MB cache
2 GB DDR2 SDRAM at 800 MHz
16x DVD-ROM and 16X DVD + /-RW
Nvidia GeForce 9800GT
300 GB SATA Hard Drive (10KRPM) Western Digital 150 VR
SP1 Windows Vista Home Premium 64-Bit Edition

Computer # 1 is my current team. I had many problems with it and sent me a Dell computer # 2 as a replacement. I asked myself what improvements, rebates or other information is collected from someone, the pros and cons?

Thank you very much for your help!