Don't go for a windowed LED case, they look tacky for business use. (Personally, I'm not a fan of them at all, but that's another matter)
Go for something neutral, or something sleek like this..
http://www.overclockers.co.uk/showproduct.php?prodid=CA-268-LL&groupid=2362&catid=187

I think this is as cheap as your going to get it without getting rid of the office software and windows (doesn't have a machine that he can use the OS and the Office software from already?).
YOUR BASKET
1 x Microsoft Office Home and Business 2013 x32/x64 English - (PKC) Product Key Card (MRS-T5D-01574) £199.99
1 x Intel Core i5-4440 3.10GHz (Haswell) Socket LGA1150 Processor - Retail £139.99
1 x Iiyama Prolite E2482HSD 24" Widescreen LED Monitor - Black £119.99
1 x MSI Z87-G43 Intel Z87 (Socket 1150) DDR3 ATX Motherboard £95.99
1 x Samsung 120GB SSD 840 EVO SATA 6Gb/s Basic - (MZ-7TE120BW) £86.99
1 x Microsoft Windows 7 Home Premium SP1 64-Bit - OEM (GFC-02050) £83.99
1 x Seagate Barracuda 7200RPM 1TB SATA 6Gb/s 64MB Cache - OEM (ST1000DM003) HDD £53.99
1 x Crucial Ballistix Sport 8GB (2x4GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit (BLS2CP4G3D1609DS1S00CEU) £49.99
1 x Corsair Builder Series CX 430W V2 '80 Plus Bronze' Power Supply (CP-9020046-UK) £39.95
1 x Xigmatek Asgard Pro Gaming Case - Black £32.99
1 x Cooler Master Hyper 212 Evo CPU Cooler £26.99
1 x OcUK 24x DVD±RW SATA ReWriter (Black) - OEM £16.99
Total : £970.75 (includes shipping : £19.10).
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just want to show you this as well
http://www.overclockers.co.uk/showproduct.php?prodid=CA-087-BX&groupid=2362&catid=1850
So so can you use Windows 8 (free Trial) for 3 months and save up for Windows 7? and use open office as its free?

Or this.
YOUR BASKET
1 x Corsair Carbide 330R Silent Mid Tower Case - Black £74.95
Total : £86.05 (includes shipping : £9.25).
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