Samsung galaxy spica, probably the best budget android mobile considering it has the best hardware specs apart from the camera which isn't the best tbh, better than the HTC hero and the HTC wildfire, sony Ericsson mini pro etc. for hardware specs IMO.
Some basic specs to give you an idea:
(Your mobile) 5800 specs:
CPU ARM 11 434 MHz processor
Internal 81 MB storage, 128 MB RAM
TFT resistive touchscreen, 16M colors
Size 360 x 640 pixels, 3.2 inches
Standard battery, Li-Ion 1320 mAh(BL-5J)
Symbian OS v9.4, Series 60 rel. 5
Camera 3.15 MP, 2048x1536 pixels, Carl Zeiss optics,
Video Yes, VGA@30fps
Samsung Galaxy Spica I5700:
CPU 800MHz processor
Internal 180 MB storage
TFT capacitive touchscreen, 16M colors
Size 320 x 480 pixels, 3.2 inches
Standard battery, Li-Ion 1500 mAh
Android 2.1 OS
Camera 3.15 MP, 2048x1536 pixels, autofocus
Video Yes, CIF@15fps
HTC Wildfire:
CPU Qualcomm MSM 7225 528 MHz processor
Internal 384 MB RAM; 512 MB ROM
TFT capacitive touchscreen, 16M colors
Size 240 x 320 pixels, 3.2 inches
Standard battery, Li-Ion 1300 mAh
Android 2.1 OS (but getting the update to 2.2)
Camera 5 MP, 2592 x 1944 pixels, autofocus, LED flash
Video Yes
HTC Hero:
CPU Qualcomm MSM 7200A 528 MHz processor
Internal 288 MB RAM, 512 MB ROM
Type TFT capacitive touchscreen, 65K colors (think it's 16 million colours though)
Size 320 x 480 pixels, 3.2 inches
Standard battery, Li-Ion 1350 mAh
Android 2.1 OS
Camera 5 MP, 2592 x 1944 pixels, autofocus
Video Yes, CIF@15fps
Personally I would not even consider the wildfire even though it is fairly nice looking mobile and the specs are decent plus the main thing is that's getting 2.2, but unfortunately the screen resolution is awful, some people have mentioned that you can actually see the individual pixels and also some apps will not work due to this for e.g. the Engadget app, plus it would be awful for web browsing and watching videos.
EDIT: The only thing which the HTC mobiles have over the other mobiles like samsung etc. is the HTC sense UI, however that's down to personal preference, I quite like it in some ways but rather have just stock android and also a lot of people who have the desire on this forum don't like the sense UI and so they have flashed custom firmwares on to there mobiles to get rid of it. Plus you will probably end up using launcher pro (that's if you buy an android mobile) instead for it's pure speed and full customization of your mobile and also it has widgets which are very similar to HTC sense ones now. Also if you wanted you could make your samsung or other non HTC mobile look like sense.
If you want a mobile for the camera, the HTC wildfire would probably be worth considering or the sony ericsson mini, hero as well but it doesn't have a flash so would be useless for photos in the dark.
And for music, I would say that all mobiles would be just as good as each other for that tbh.
Also it depends if your going to root and flash custom firmwares on your mobile as HTC would have a much better developing community but samsung also has a very good developing community at samdroid.net. For e.g. someone has got flash working on the samsung I5700 2.1 (was only able to work on 2.2), leshak is working on 2.2 for the I5700, developers are working on implementing the multi touch feature which hasn't been unlocked on the i5700 yet and also improving the 3d driver as well (originally couldn't play the raging thunder racing game but now you can, apparently it's very smooth but some textures missing etc. but no doubt those will be fixed very soon).
Have a look at this thread for more info on the best budget mobile, also I have another post there which goes into more detail about some of the mobiles:
http://forums.overclockers.co.uk/showthread.php?p=16987341#post16987341
EDIT: I would get a capacitive touch screen mobile any day rather than a resistive touch screen (but that's personal preference really), mainly due to resistive being so annoying to use, having to actually push the screen in with a finger nail to select something, where as with capacitive, just the slightest touch and you can select something with ease.
You really just need to try the mobiles out for yourself to see which one suits you best.
but not sure whether to get the same again or have a look about and see what my other options are. Will be using my phone to double up as an mp3 player as well as using it for general internet tasks when out and about.
