Offtek are also quite good, I have used them for several systems in the past also: [URL]  They are slightly cheaper than Crucial for this model but theres not that much difference. [URL]  The .iso idea should work there has been a large number of people who have followed my guide without incident. Let us know how it goes. One other thing to also consider is using a Solid State Drive as a boot drive, this would make the system alot faster.
I have had my Dell Studio 540 Desktop since August 2009, it has worked OK so far. I have investigated about installing Win7 64 bit to get better use from the 4GB Ram - with a view to getting the RAM increased to 8GB.  I followed the MS guides about backing up software and data and ensuring the data is safe, but as it stated I had to go into the Windows and select a manual instal to get to the options  to choose the 64 bit Option, I got the disks out from Dell (opened new software disks some 4 years after getting the PC. I then spotted the disks stated they had 32 bit versions only!  :emotion-6:   Now can Dell send me the required disk on a free or 1 for 1 swap basis? Or will I have to pay to get a 64bit version of Win 7 - if so how much? Before it is suggested - I have no wish to upgrade to Windows 8.  Any help appreciated.   :emotion-1:
Win7 options on Supplied Dell disks