So my XPS m1730 (specs in sig) had its graphics card burn out and Dell is replacing it with the Alienware M17X (Specs Below).

I have a few questions that hopefully you folks can help me out with:

1. My m1730 had a T8300 Processor and they are putting a P8600 Processor in the M17X. Whats the difference? Is the P8600 better? Will I notice a performance difference?

2. I have Vista Business 64 bit and they are giving Vista Home Premium in the M17X, is there a big difference in the OS? I suppose I can reformat with my Vista Business Disk, but is it necessary?

3. I can buy 4 gigs of 1333mhz ram for like $80, will I notice a big difference between the 1066mhz and the 1333mhz?

4. My warranty is running out on 1/2010 and since the replacment they are giving me is brand new, can I buy another extended warranty for 3 years and pay for it out of pocket?

M17X Specs:

1 224-5967 Black Metallic
1 310-0173 Airborne Documentation, System Exchanges,Factory Install
1 313-7711 Slot-Loading Dual Layer DVD Burner (DVD+-RW, CD-RW)
1 317-0819 Intel Core2 Duo P8600 2.4GHz (3MB Cache, 1066MHz FSB)
1 317-0856 4GB Dual Channel DDR3 at 1066MHz 2 x 2048MB
1 320-1000 1GB Dual NVIDIA GeForce GTX 260M - SLI Enabled (NB10E-GT1)
1 320-8140 17.0in, WUXGA,LCD,ANW,M17X
1 330-5063 Standard Nameplate
1 330-5414 Windows 7 Home Premium UpgradeCoupon, W0, ENG,SPN,FRE,GER JPN
1 341-0011 250GB 7,200RPM (xMB Cache) w/ Free Fall Protection
1 410-0173 ADOBE ACROBAT READER - Eng
1 420-3251 Windows Vista Home Premium (64-bit Edition) with Service Pack 1
1 421-0360 Avatar1
1 421-0381 RSS Feeds,AW
1 421-0389 Window Style, DFT
1 421-0398 Power Plan, BAL
1 421-0399 Time Zone, CENTRAL
1 421-0405 Automatic Updates ON
1 421-0415 Mouse Pointers,STANDARD
1 421-0726 ALIENFX BLUE
1 421-1724 Soft Contracts,Dell In Home,Alienware
1 430-0628 Bluetooth 2.1 with EDR
1 430-3558 Internal 300Mbps Dual-Band a/g/n 2x2 MIMO