Need Help. Looking for a PC capable of Crysis 2 & Witcher 2 with �450 Budget?

Im looking iinto buying a new PC for gaming but im a complete N00B ... I have no idea how to build one or which specs are better than others. So i would love help on finding a PC capable of games like Crysis 2 under a tight budget. I found this http://www.geforce.com/#/Optimize/Guides/how-to-build-a-kick-***-crysis-2-pc-for-under-600 and when i converted the dollars to GBP it was within budget but are these specs already outdated and of course i cant build it myself ... please help links would be appreciated