Switch to UEFI boot with windows 7

Hello, I bought a Precision M4800 laptop, which has legacy boot option set by default. I would like to switch to UEFI, which apparently requires a complete reinstall of windows. I don't know which partitioning tool to use, what partitions do I need and most importantly, whether I need to buy a windows installation disc. I have a windows recovery partition and I could use it to restore to factory settings - which would again use legacy boot. Is there a way for me to switch to UEFI without having to buy a new copy of windows? I haven't found any information on the Dell website ...

 I also tried to switch the boot option from legacy to UEFI in bios, but I ended up with an error message after restarting - "No bootable device found". Since I don't have a GPT partition, this is no surprise I suppose.

Thank you for any information that will help me to setup windows 7 with UEFI. I would also be very grateful for any report regarding dual installation windows 7/archlinux in case there's such a user here.