Hello Mawgwr
The Microsoft Answers community is supported by users such as you and Zilo. No one here gets paid. Most of the information found here is provided by the members and their time is volunteered. With that said, Zilo was only pointing you to a community geared more specifically to your system.
As for your issue, installing Windows XP is not your biggest problem at the moment, the system not booting up and giving beep codes is. This is an indication that the hardware has possibly failed in some way. I have found some information regarding beep codes for your system. However, of the listed codes found only 1 seems to fit as you have described. 1 long beep and 3 short beeps. This is an indication of memory failure. My suggestion would be to try and boot from only one stick of memory and see fit the system loads or you could contact Fujitsu for hardware support. Thanks.