According to the datasheet the fastest CPU you can install is the AMD Athlon 64 Tk-53 (1.7GHz). But since the Turion 64 X2 TL-52 is supported too, I'd be optimistic that also the Trinidad version of the TL-64 (2.2GHz) will work.
Maybe even the TL-68 (2.4GHz) will work, but since the specifications of the BIOS are closed I can't tell for sure.
For the HDD maybe it will help to install one with 7200rpm. But I'm not sure if your controller can handle the increased power consumption.
Another option migt be a fast SSD. Just recently a user in the german amilo-forum posted some benchmarks for some solid state drives which look quite impressive:
https://www.amilo-forum.de/topic,29045,-60-GB-SOLID-STATE-DISK-SSD-2-5.htmlI think the screenshots speak for themselves. The first three are from his Amilo Xi 2550 while the last one is from his Akoya mini netbook where he suspects the Atom CPU to slow down the SSD.