Are you gaming? If not a £600-£700 17" will be more than plenty, and have 2GB, 2ghz dual core Intel 2, and 160GB+ HD. £2500 on a laptop if you're not gaming is just a waste of money.
I like Acer's, because of the cost/spec, there's the Gemstore Aspire 77xx line. £700 inc vat gets you this
Product Description - Acer Aspire 7720 - Core 2 Duo T7300 - 17" TFT
Dimensions (WxDxH) - 40.4 cm x 29.8 cm x 4.3 cm
Weight - 3.6 kg
Localisation - United Kingdom
Platform Technology - Intel Centrino Duo
System Type - Notebook
Built-in Devices - Stereo speakers, subwoofer, wireless LAN aerial, Bluetooth aerial
Processor - Intel Core 2 Duo T7300 ( Dual-Core )
Cache Memory - 4 MB - L2 Cache
RAM - 2 GB (installed) / 4 GB (max) - DDR II SDRAM ( 2 x 1 GB )- Low cost double memory offer, call for details!
Card Reader - 5 in 1
Hard Drive - 160 GB - Serial ATA-150
Hard Drive (2nd) - 160 GB - Serial ATA-150
Optical Storage - HD DVD-ROM - integrated
Display - 17" TFT active matrix 1440 x 900 ( WXGA+ ) - 24-bit (16.7 million colours)
Graphics Controller - ATI Mobility Radeon X2300 - 256 MB
Audio Output - Sound card
Telecom - Fax / modem - 56 Kbps
Networking - Network adapter - Ethernet, Fast Ethernet, Gigabit Ethernet, IEEE 802.11b, IEEE 802.11a, IEEE 802.11g, IEEE 802.11n (draft), Bluetooth 2.0 EDR
Wireless NIC - Intel Wireless WiFi Link 4965AGN
Notebook Camera - Integrated - 0.3 Megapixel
Input Device - Keyboard, touchpad, 4-way scroll button
Power - AC 120/230 V ( 50/60 Hz )
Battery - Lithium Ion
Operating System - Microsoft Windows Vista Home Premium
Manufacturer Warranty - 1 year warranty
Acer Aspire 7720 Gemstone Laptop - LX.AK10U.037