Take your pick;
http://www.google.co.uk/search?hl=en&q=diy+window+installation&meta=
You need to seriously weigh up the pros & cons of a DIY install, it’s not rocket science but there are many opportunities to make costly mistakes;
• Getting the sizes wrong
• Breaking the glass
• Installing the frames or glass incorrectly
• LABC inspection & the fee
• Compliance with BR’s & getting that all important compliance certificate
• After service & warranty claims
• Independent 10 year warranty (although the value of some is questionable)
• Disposing of your old windows
• It may take you 3 weeks+ to remove & install whereas a couple of pro fitters will probably take less than 3 days
Not many DG companies make their own units now, even some of the large nationals; very often, small local companies can supply the same units much more competitively & make a better job of installing them. If you use a small local company who supplies & installs good quality products, DIY may not save you as much money as you think. They will be able to supply branded products direct from the factory much cheaper than you can get them for & the fitting charge per unit may not be as much as you think; this usually averages between £50 -£100 depending on window/door size & the company. There are companies that specialise in the manufacture of products specifically for the DIY market but I would advise caution & I wouldn’t buy from anyone unless I could inspect the product.
You also need to ensure your comparing like with like on product quality; there can be significant differences & the installation can make or break a job. You hear the horror stories all the time & there are some real cowboys around but if you use a small local company on recommendation, you will reduce the risk significantly as their reputation is their livelihood, even more so in the current climate.