Hello everyone,
First post (and quite involved) so please be gentle with me

Any advice is much appreciated as I'm stuck on how to move forward but desparately want to melt some plastic!
I'm currently looking to upgrade my system and I could really do with some advice. I'm a bit behind with my current system and am looking to upgrade while hopefully (physically) shrinking the system (due to wifely constraints and the fact our new living room is none too massive). I have a budget of around £600. I'll give you an idea of what I'm working with, which is a bit of a masmitch

...
Sony Amp TA-AV570 (ProLogic only- This is a reasonable old thing but pumps out decent music)
Marantz CD63 MkII KI. Obviously not going anywhere

Speakers:
Mordaunt Short MS3-30 fronts
Yamaha YST150 Sub
Jamo II wall mounted rears
Sony cheapo centre
QED Anniversary 25 cables
... and obviously DVD and telly
I've been missing out on 5.1 with my amp and I know it, but don't watch millions of films, hence the budget. I'm really not sure what to go for. I like my music (500 rock/indie/dance CDs) and the M-S speakers are good. I really don't want to lose music quality but then again they are 10 years old so may not be as good as I thought compared to current available systems!
The way I see it, several options are available to me:
1. Blow the lot on a set of matched box speakers + sub. Some I've seen while surfing have included Monitor Audio Baby system, or the Mirage AVS500/FRX-S8 microsystem. These were off the home entertainment website and got favourable reviews.
2. Another option is the FS2AVs but I understand these need quite a pokey amp. Mine may not be capable of driving these. As they seem to be going for <>£400 then perhaps a cheap(ish) 5.1 amp may be within budget to go with them ).
3. Stick to what I have for music and get a speaker/sub/decoder set for the movies for around £3-400 and save some beer tokens.
Obviously any of the above will free up HW to go in the classified sections
Oh and just to drive the final nail into my confusion, the wife has to like them so no chance of the KEF eggs, and if the speakers come in white they get a definite thumbs up.
Any help or advice you lot can give me on deciding the right track would be gratefully received.
Confused Joolz