Desire a change to Libreoffice

At present I use Open Office I recently came across a posting about Libreoffice which sounded interesting. Libreoffice advise that Open office documents should be saved and then the software should be deleted before downloading Libreoffice. In theory I understand that - but how do I save my spreadsheets with my information if there is no framework to hold the info in place? I guess I am hoping that somehow I can just click ??? and my information will miraculously appear correctly on Libreoffice spreadsheets.

Please make the advice really simple!! Thank you

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows XP Professional, Service Pack 3, 32 bit
Processor: Intel(R) Celeron(R) CPU 2.80GHz, x86 Family 15 Model 2 Stepping 9
Processor Count: 1
RAM: 2015 Mb
Graphics Card: SiS 650, 32 Mb
Hard Drives: C: Total - 76308 MB, Free - 51727 MB;
Motherboard: NEC COMPUTERS INTERNATIONAL, GA-8SIMLNF
Antivirus: avast! Antivirus, Updated: Yes, On-Demand Scanner: Enabled