At the moment i've got an old Kenwood stereo system, with a pretty poor sub i got with an all in one 5.1 surround sound system a while ago. I want to upgrade, but I don't know which option would be better.

1. Scrap the stereo and the sub and buy a pair of floorstanders
2. Buy a new sub, fit bass blockers with the speakers for the time being, and upgrade at a later date.

The speakers atm aren't bad (for my standard at least, they win hands down against 95% of the speakers people i know own), only 80watt (the model's RXD-G4 if anyone knows about it) but good quality. The system cost around 450-500 when bought.

I wanted to go for the floorstanders idea to begin with (was looking at a pair of Eltax Sympony 8.2's) as it'd be cheaper overall. I'm at uni atm so i really can't afford too much, hence been looking on ebay for speakers rather than brand new from the shops.
However, floorstanders i think are less versatile than having a seperate sub and bookshelf speakers, and i'm not sure if i could cope with trying to move them when i leave this house.
The second idea would be easier, as it doesn't have to be done all at once. Though i don't know much about subs, and i don't want to either end up buying a cheap sub that sounds bollocks, or spending more than i need on a sub that's better than what i need.
The reason for the bass blockers is the speakers i have atm are good, but because they try and reproduce bass themselves, you get awful distortion on the lower end, while the higher frequencies still sound pretty good. If i get a new sub i wont need them to produce any bass, and can wait 'til i get new speakers.
Also pretty sure either way i'll need to buy an amp at some point. Not sure how good the stereo is in that department.

I don't know much about audio atm, just tryin to get some knowledgable help
Budget right now is probably only 200-250. I'm not quite sure at the moment tho!