hi leorc,
for alpari uk micro account: max 2 lots (open positions)
classic and pro account: no limit
http://www.alpari.co.uk/en/trading_accounts/account_comparison_table.html
i'm on mission since 11th Feb 2010.
Start with 600 Euro
First target: 1.000.000 Euro
preparation time 3 years.
(spike is because broker had a credit bonus campaign (in/out))