Hi Nick,
I own and use the DVE ( Digital Video Essentials) HD Basics disc. Great menus, uses included glasses to get the correct colour balance and although the language for use is a little confusing first time around just listen again. Picked my copy up for £15 from Amazon. You will hear of this disc used a lot in 'Home Cinema Choice'. Just look on Amazon for some reviews. Makes a HUGE difference to performance. You can get a nice blend of contrast and edge definition. Just be sure to turn all extra processing off before you start.
Lastly, great to see somebody trying to maximise their own kit before mentioning the worth of £100 HDMI leads and 6 monthly Blu-Ray player changes. Nice one Nick.
'If you're current kit aint running at its best then how can you make a thorough comparison when adding new kit'
I have 3 top 'bargain' things - firstly - DVE disc for £15, Tacima Mains Conditioner £30, & That Cable HDMI £5 = £50 for bargain performance boost.
Good Luck,
Cookie Monster