How to install Windows 7 from Windows XP w/o losing any file

Hi! I’m planning to install Windows 7 Ultimate SP1 (32 bit) from my Windows XP SP3 but I can’t upgrade it ’cause it won’t let me to. Which means I have to choose Custom Installation but I can’t continue ’cause it will delete my files. Can anybody please help me or show me a step by step instruction on how to install windows 7 without losing any of my files? is it possible? It’s my first time installing a new OS. I just wanna be cautious before I proceed. BTW I got Windows 7 from this thread http://www.google.com?t=17275861&highlight= is it a good source to get windows 7 or can you recommend a better one? Thanks you so much in advance.
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Answer #1
Do a dual boot..Installing Windows 7 over XP can end up in disaster..
You can keep your XP and install a fresh Windows 7..
How to Dual Boot Windows 7 with XP – Tutorial:
http://lifehacker.com/5126781/how-to-dual-boot-windows-7-with-xp-or-vista
Answer #2
Back everything up and install fresh.