You could try Windows 7 32 bit, some old software will work on the 32 bit that doesn't work on the 64 bit particularly if you run it in compatibility mode. Dell have a full set of Windows 7 32 bit drivers for this model but don't list them. I have listed them here.  If it is just one piece of software probably the easiest way forward is to keep your Windows 7 64 bit installation. Then install Oracle VirtualBox and install Windows XP as a virtual machine. On the virtual machine install your software and run it as normal. I would recommend maximising your RAM to 8 GB if you don't already have 8 GB (the part is best obtained from crucial here). This will allow you to give the virtual machine 2-4 GB of RAM, so it isn't painfully slow. Alternatively upgrade to Windows 7 Professional and use XP Mode. I prefer using virtualbox to XP mode however as XP Mode does seem slower than VirtualBox.  
Hi to all.. I have installed the windows XP on my Inspiron N5110.  Because my company software only run on Windows XP or 98.. So please I need all driver for N5110. Like Video, Audio, Wifi, Lan and all other. So please help me where from I can download the drivers..  Regards Asif
INSPIRON N5110 Drivers require for WINDOWS XP