Lot of stuff we could use more details on..
Preference on monitor size? I realize you say rules can't change, but why only Dell? There's plenty of other reputable brands available with competitive pricing.. What kind of games is 'he' looking to play, new or older?
The computer JCB linked to there would be a very quick machine. He has a good suggestion with the SSD, with processors as fast as they are now accessing data is becoming the bottleneck. Also, if you do purchase that machine, I'd consider upgrading the GPU to something a bit better if 'he' wants to do some more serious gaming.
-Desktop- Dual Monitor, Q8200 2.34Ghz, 8GB, 1TB, XFX 6850, 7 Ultimate
-ASUS UL50- SU7300, 4GB, 500GB, G210M, 7 Home Premium 64, XP Pro
-HP NC6400- Core Duo 1.86Ghz, 2.5GB, 64GB SSD, x1300, XP Pro