[Hampshire] Sempron or Celeron

Hi All,

I'm considering upgrading out home laptop with a cheap Dell. The
choice is either a Sempron Mobile 3500, or a Celeron M 520?

Each offering also has an upgrade. The Sempron Mobile 3500 to Athlon
64x2 TK53 for £47, or the Celeron M 520 to a Dual Core T2080 (for
£23.50) or T2130 for £47.

It will mainly be used for word processing etc, email & web. However
my Desktop has an Athlon Xp, and I am constantly suprised that the
amount of software that requires an Intel CPU to run.

So what are the pros/cons of each, and what would you recommend?
Budget £400, £450 at a push.

Cheers,
Chris