If you need Vista and a keyboard as well as the base unit this is what I'd go for.
GeIL 2GB (2x1GB) PC6400C4 800MHz Ultra Low Latency DDR2 Dual Channel Kit (GX22GB6400UDC) £97.99
(£115.14) £97.99
(£115.14)
Asus P5N-E SLi nForce 650 (Socket 775) PCI-Express DDR2 Motherboard £69.99
(£82.24) £69.99
(£82.24)
OcUK GeForce 8800 GTS 320MB GDDR3 HDTV/Dual DVI (PCI-Express) - Retail £163.99
(£192.69) £163.99
(£192.69)
Seagate Barracuda 7200.10 250GB ST3250620AS SATA-II 16MB Cache - OEM £46.99
(£55.21) £46.99
(£55.21)
NEC AD7170S Serial ATA 18x18 DVD±RW Dual Layer ReWriter (Black) - OEM £18.99
(£22.31) £18.99
(£22.31)
Tuniq Tower 120 CPU Cooler £29.99
(£35.24) £29.99
(£35.24)
Microsoft Windows Vista Home Premium 64-Bit Edition DVD - OEM - 1Pk (66I-00788) £61.99
(£72.84) £61.99
(£72.84)
Microsoft Comfort Curve 2000 Keyboard £11.99
(£14.09) £11.99
(£14.09)
Antec NSK6500 Super Midi Tower Case - 430W PSU £58.99
(£69.31) £58.99
(£69.31)
Intel Core 2 DUO E6300 "LGA775 Allendale" 1.86GHz (1066FSB) - Retail £101.99
(£119.84) £101.99
(£119.84)
Sub Total : £662.90
Shipping cost assumes delivery to UK Mainland with:
City Link Parcel Next Day (Delivered Mon-Fri)
(This can be changed during checkout) Shipping : £10.95
Vat : £117.92
Total : £791.77