Need a little help

Hi all, new to this so il be as precise as possible. I have been recently looking in to build my own but i recently came across a deal from dell , il give the specs
XPS 8300
..Intel® Core™ i7-2600 Processor (3.40GHz, 8MB)
..Blu-Ray ROM combo (Blu-ray read only, DVD, CD read & write) (999 euro)
..8192MB Dual Channel DDR3 1333MHz [4x2048] Memory
..2TB Dual Hard Drive RAID 0 "Stripe" (2x1TB - 7,200 rpm)
..AMD Radeon™ HD 6770 1GB DDR5 graphics

At the mo its on offer for about 40% off, fairly decent offer but im more concerned whit up grading and was wondering how easy the dell are to up grade and what sort of motherboard they run on. so if you people have any input cause im a little torn   but i have been looking online and though i have never built a pc i am well capable but i have messed whit loads of set ups online. All that said i would like to add a little side note, my budget is around 1300 euro could any body throw a few different set ups at me need a fresh perspective on building for that budget mainly done the builds on komplett for that budget mainly gaming. I'm in Ireland so a local view would be nice as well
And i need to squeeze a monitor in there as well
Thank you