Major Computer Upgrade Decision that i need to make in 2 days, HELP!

Alright guys, dell has just given me a great offer. Here it is:

Dimension 3100 Desktop with 1GB ram and 19" flat panel upgrade
Intel Pentium 4 Processor 524 with HT Technology (3GHz, 1MB L2 Cache, 533MHz FSB)
Windows XP Home Edition
1GB shared Dual-Channel DDR2 SDRAM
80 GB SATA Hard Drive
Intel Graphics Media Accelerator 900
48x CD-ROM Drive
Integrated 10/100 Ethernet
1-Yr economy service plan
Dell E196FP 19" Flat Panel Display

All for $449

I'm going to call and see if my Antec 430 watt PS and geforce 6800 card is compatible. If it is, then I'm really thinking about going with this. My current setup that it will replace is:

AMD Athlon 2500+ XP (1.83GHz)
1 GB ram (not PC3200)
geforce 6800 video card
16 GB hard drive
Antec PS
Huge 17" monitor (I mean GIGANTIC )

My current setup has problems running Counter Strike 1.6. Is the processor in the dell a lot better? And should i be able to run CS:S well? How well of a system is this for multitasking (the dell)?

Thanks a bunch, I have 2 days to purchase this deal, or it will expire.