Can i use windows 7 on my old machine:
AMD Sempron LE-1100 1.90 Ghz (1 Core)
2 GB RAM DDR2
Motherboard:MSI K9N6PGM2-V2
Graphics CardOnboard):Nvidia Geforce 7025/nForce 630a
It will do just about. If you have a spare £20 - £40 you can upgrade your CPU to a dual core Athlon which would give a nice performance boost. Here is a comparison between your CPU and a old Athlon dual core that can be found probably be found for less than £20 on eBay without a heatsink (you should be able to pick a heatsink good enough for that CPU for £10 to £15 easily).