For the moniter I would personally spend a little extra and get the E-IPS Dell 2209W.
£159.85 + shipping from PC Buy It (VAT inc)
E-IPS panels have faster response rates and better colour definition than TN panels. With calibration they can also provide perfect (i.e. the same as real world results) colour definition. But for gaming the main advantage is response time, and for general use, the deeper blacks will be an advantage.
For keyboard and mouse? Well that's personal perference. I recommend the MX1100 coupled with a G15, but you might not like the LCD display of the G15, want a wired mouse, etc.